12025cf9eSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 2d475c634SMatthew Wilcox /* 3d475c634SMatthew Wilcox * fs/dax.c - Direct Access filesystem code 4d475c634SMatthew Wilcox * Copyright (c) 2013-2014 Intel Corporation 5d475c634SMatthew Wilcox * Author: Matthew Wilcox <matthew.r.wilcox@intel.com> 6d475c634SMatthew Wilcox * Author: Ross Zwisler <ross.zwisler@linux.intel.com> 7d475c634SMatthew Wilcox */ 8d475c634SMatthew Wilcox 9d475c634SMatthew Wilcox #include <linux/atomic.h> 10d475c634SMatthew Wilcox #include <linux/blkdev.h> 11d475c634SMatthew Wilcox #include <linux/buffer_head.h> 12d77e92e2SRoss Zwisler #include <linux/dax.h> 13d475c634SMatthew Wilcox #include <linux/fs.h> 14f7ca90b1SMatthew Wilcox #include <linux/highmem.h> 15f7ca90b1SMatthew Wilcox #include <linux/memcontrol.h> 16f7ca90b1SMatthew Wilcox #include <linux/mm.h> 17d475c634SMatthew Wilcox #include <linux/mutex.h> 189973c98eSRoss Zwisler #include <linux/pagevec.h> 19289c6aedSMatthew Wilcox #include <linux/sched.h> 20f361bf4aSIngo Molnar #include <linux/sched/signal.h> 21d475c634SMatthew Wilcox #include <linux/uio.h> 22f7ca90b1SMatthew Wilcox #include <linux/vmstat.h> 2334c0fd54SDan Williams #include <linux/pfn_t.h> 240e749e54SDan Williams #include <linux/sizes.h> 254b4bb46dSJan Kara #include <linux/mmu_notifier.h> 26a254e568SChristoph Hellwig #include <linux/iomap.h> 2706083a09SMuchun Song #include <linux/rmap.h> 2811cf9d86SAneesh Kumar K.V #include <asm/pgalloc.h> 29d475c634SMatthew Wilcox 30282a8e03SRoss Zwisler #define CREATE_TRACE_POINTS 31282a8e03SRoss Zwisler #include <trace/events/fs_dax.h> 32282a8e03SRoss Zwisler 33cfc93c6cSMatthew Wilcox static inline unsigned int pe_order(enum page_entry_size pe_size) 34cfc93c6cSMatthew Wilcox { 35cfc93c6cSMatthew Wilcox if (pe_size == PE_SIZE_PTE) 36cfc93c6cSMatthew Wilcox return PAGE_SHIFT - PAGE_SHIFT; 37cfc93c6cSMatthew Wilcox if (pe_size == PE_SIZE_PMD) 38cfc93c6cSMatthew Wilcox return PMD_SHIFT - PAGE_SHIFT; 39cfc93c6cSMatthew Wilcox if (pe_size == PE_SIZE_PUD) 40cfc93c6cSMatthew Wilcox return PUD_SHIFT - PAGE_SHIFT; 41cfc93c6cSMatthew Wilcox return ~0; 42cfc93c6cSMatthew Wilcox } 43cfc93c6cSMatthew Wilcox 44ac401cc7SJan Kara /* We choose 4096 entries - same as per-zone page wait tables */ 45ac401cc7SJan Kara #define DAX_WAIT_TABLE_BITS 12 46ac401cc7SJan Kara #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) 47ac401cc7SJan Kara 48917f3452SRoss Zwisler /* The 'colour' (ie low bits) within a PMD of a page offset. */ 49917f3452SRoss Zwisler #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) 50977fbdcdSMatthew Wilcox #define PG_PMD_NR (PMD_SIZE >> PAGE_SHIFT) 51917f3452SRoss Zwisler 52cfc93c6cSMatthew Wilcox /* The order of a PMD entry */ 53cfc93c6cSMatthew Wilcox #define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT) 54cfc93c6cSMatthew Wilcox 55ce95ab0fSRoss Zwisler static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; 56ac401cc7SJan Kara 57ac401cc7SJan Kara static int __init init_dax_wait_table(void) 58ac401cc7SJan Kara { 59ac401cc7SJan Kara int i; 60ac401cc7SJan Kara 61ac401cc7SJan Kara for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++) 62ac401cc7SJan Kara init_waitqueue_head(wait_table + i); 63ac401cc7SJan Kara return 0; 64ac401cc7SJan Kara } 65ac401cc7SJan Kara fs_initcall(init_dax_wait_table); 66ac401cc7SJan Kara 67527b19d0SRoss Zwisler /* 683159f943SMatthew Wilcox * DAX pagecache entries use XArray value entries so they can't be mistaken 693159f943SMatthew Wilcox * for pages. We use one bit for locking, one bit for the entry size (PMD) 703159f943SMatthew Wilcox * and two more to tell us if the entry is a zero page or an empty entry that 713159f943SMatthew Wilcox * is just used for locking. In total four special bits. 72527b19d0SRoss Zwisler * 73527b19d0SRoss Zwisler * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE 74527b19d0SRoss Zwisler * and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem 75527b19d0SRoss Zwisler * block allocation. 76527b19d0SRoss Zwisler */ 773159f943SMatthew Wilcox #define DAX_SHIFT (4) 783159f943SMatthew Wilcox #define DAX_LOCKED (1UL << 0) 793159f943SMatthew Wilcox #define DAX_PMD (1UL << 1) 803159f943SMatthew Wilcox #define DAX_ZERO_PAGE (1UL << 2) 813159f943SMatthew Wilcox #define DAX_EMPTY (1UL << 3) 82527b19d0SRoss Zwisler 83a77d19f4SMatthew Wilcox static unsigned long dax_to_pfn(void *entry) 84527b19d0SRoss Zwisler { 853159f943SMatthew Wilcox return xa_to_value(entry) >> DAX_SHIFT; 86527b19d0SRoss Zwisler } 87527b19d0SRoss Zwisler 889f32d221SMatthew Wilcox static void *dax_make_entry(pfn_t pfn, unsigned long flags) 899f32d221SMatthew Wilcox { 909f32d221SMatthew Wilcox return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT)); 919f32d221SMatthew Wilcox } 929f32d221SMatthew Wilcox 93cfc93c6cSMatthew Wilcox static bool dax_is_locked(void *entry) 94cfc93c6cSMatthew Wilcox { 95cfc93c6cSMatthew Wilcox return xa_to_value(entry) & DAX_LOCKED; 96cfc93c6cSMatthew Wilcox } 97cfc93c6cSMatthew Wilcox 98a77d19f4SMatthew Wilcox static unsigned int dax_entry_order(void *entry) 99527b19d0SRoss Zwisler { 1003159f943SMatthew Wilcox if (xa_to_value(entry) & DAX_PMD) 101cfc93c6cSMatthew Wilcox return PMD_ORDER; 102527b19d0SRoss Zwisler return 0; 103527b19d0SRoss Zwisler } 104527b19d0SRoss Zwisler 105fda490d3SMatthew Wilcox static unsigned long dax_is_pmd_entry(void *entry) 106642261acSRoss Zwisler { 1073159f943SMatthew Wilcox return xa_to_value(entry) & DAX_PMD; 108642261acSRoss Zwisler } 109642261acSRoss Zwisler 110fda490d3SMatthew Wilcox static bool dax_is_pte_entry(void *entry) 111642261acSRoss Zwisler { 1123159f943SMatthew Wilcox return !(xa_to_value(entry) & DAX_PMD); 113642261acSRoss Zwisler } 114642261acSRoss Zwisler 115642261acSRoss Zwisler static int dax_is_zero_entry(void *entry) 116642261acSRoss Zwisler { 1173159f943SMatthew Wilcox return xa_to_value(entry) & DAX_ZERO_PAGE; 118642261acSRoss Zwisler } 119642261acSRoss Zwisler 120642261acSRoss Zwisler static int dax_is_empty_entry(void *entry) 121642261acSRoss Zwisler { 1223159f943SMatthew Wilcox return xa_to_value(entry) & DAX_EMPTY; 123642261acSRoss Zwisler } 124642261acSRoss Zwisler 125f7ca90b1SMatthew Wilcox /* 12623c84eb7SMatthew Wilcox (Oracle) * true if the entry that was found is of a smaller order than the entry 12723c84eb7SMatthew Wilcox (Oracle) * we were looking for 12823c84eb7SMatthew Wilcox (Oracle) */ 12923c84eb7SMatthew Wilcox (Oracle) static bool dax_is_conflict(void *entry) 13023c84eb7SMatthew Wilcox (Oracle) { 13123c84eb7SMatthew Wilcox (Oracle) return entry == XA_RETRY_ENTRY; 13223c84eb7SMatthew Wilcox (Oracle) } 13323c84eb7SMatthew Wilcox (Oracle) 13423c84eb7SMatthew Wilcox (Oracle) /* 135a77d19f4SMatthew Wilcox * DAX page cache entry locking 136ac401cc7SJan Kara */ 137ac401cc7SJan Kara struct exceptional_entry_key { 138ec4907ffSMatthew Wilcox struct xarray *xa; 13963e95b5cSRoss Zwisler pgoff_t entry_start; 140ac401cc7SJan Kara }; 141ac401cc7SJan Kara 142ac401cc7SJan Kara struct wait_exceptional_entry_queue { 143ac6424b9SIngo Molnar wait_queue_entry_t wait; 144ac401cc7SJan Kara struct exceptional_entry_key key; 145ac401cc7SJan Kara }; 146ac401cc7SJan Kara 147698ab77aSVivek Goyal /** 148698ab77aSVivek Goyal * enum dax_wake_mode: waitqueue wakeup behaviour 149698ab77aSVivek Goyal * @WAKE_ALL: wake all waiters in the waitqueue 150698ab77aSVivek Goyal * @WAKE_NEXT: wake only the first waiter in the waitqueue 151698ab77aSVivek Goyal */ 152698ab77aSVivek Goyal enum dax_wake_mode { 153698ab77aSVivek Goyal WAKE_ALL, 154698ab77aSVivek Goyal WAKE_NEXT, 155698ab77aSVivek Goyal }; 156698ab77aSVivek Goyal 157b15cd800SMatthew Wilcox static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas, 158b15cd800SMatthew Wilcox void *entry, struct exceptional_entry_key *key) 15963e95b5cSRoss Zwisler { 16063e95b5cSRoss Zwisler unsigned long hash; 161b15cd800SMatthew Wilcox unsigned long index = xas->xa_index; 16263e95b5cSRoss Zwisler 16363e95b5cSRoss Zwisler /* 16463e95b5cSRoss Zwisler * If 'entry' is a PMD, align the 'index' that we use for the wait 16563e95b5cSRoss Zwisler * queue to the start of that PMD. This ensures that all offsets in 16663e95b5cSRoss Zwisler * the range covered by the PMD map to the same bit lock. 16763e95b5cSRoss Zwisler */ 168642261acSRoss Zwisler if (dax_is_pmd_entry(entry)) 169917f3452SRoss Zwisler index &= ~PG_PMD_COLOUR; 170b15cd800SMatthew Wilcox key->xa = xas->xa; 17163e95b5cSRoss Zwisler key->entry_start = index; 17263e95b5cSRoss Zwisler 173b15cd800SMatthew Wilcox hash = hash_long((unsigned long)xas->xa ^ index, DAX_WAIT_TABLE_BITS); 17463e95b5cSRoss Zwisler return wait_table + hash; 17563e95b5cSRoss Zwisler } 17663e95b5cSRoss Zwisler 177ec4907ffSMatthew Wilcox static int wake_exceptional_entry_func(wait_queue_entry_t *wait, 178ec4907ffSMatthew Wilcox unsigned int mode, int sync, void *keyp) 179ac401cc7SJan Kara { 180ac401cc7SJan Kara struct exceptional_entry_key *key = keyp; 181ac401cc7SJan Kara struct wait_exceptional_entry_queue *ewait = 182ac401cc7SJan Kara container_of(wait, struct wait_exceptional_entry_queue, wait); 183ac401cc7SJan Kara 184ec4907ffSMatthew Wilcox if (key->xa != ewait->key.xa || 18563e95b5cSRoss Zwisler key->entry_start != ewait->key.entry_start) 186ac401cc7SJan Kara return 0; 187ac401cc7SJan Kara return autoremove_wake_function(wait, mode, sync, NULL); 188ac401cc7SJan Kara } 189ac401cc7SJan Kara 190ac401cc7SJan Kara /* 191b93b0163SMatthew Wilcox * @entry may no longer be the entry at the index in the mapping. 192b93b0163SMatthew Wilcox * The important information it's conveying is whether the entry at 193b93b0163SMatthew Wilcox * this index used to be a PMD entry. 194e30331ffSRoss Zwisler */ 195698ab77aSVivek Goyal static void dax_wake_entry(struct xa_state *xas, void *entry, 196698ab77aSVivek Goyal enum dax_wake_mode mode) 197e30331ffSRoss Zwisler { 198e30331ffSRoss Zwisler struct exceptional_entry_key key; 199e30331ffSRoss Zwisler wait_queue_head_t *wq; 200e30331ffSRoss Zwisler 201b15cd800SMatthew Wilcox wq = dax_entry_waitqueue(xas, entry, &key); 202e30331ffSRoss Zwisler 203e30331ffSRoss Zwisler /* 204e30331ffSRoss Zwisler * Checking for locked entry and prepare_to_wait_exclusive() happens 205b93b0163SMatthew Wilcox * under the i_pages lock, ditto for entry handling in our callers. 206e30331ffSRoss Zwisler * So at this point all tasks that could have seen our entry locked 207e30331ffSRoss Zwisler * must be in the waitqueue and the following check will see them. 208e30331ffSRoss Zwisler */ 209e30331ffSRoss Zwisler if (waitqueue_active(wq)) 210698ab77aSVivek Goyal __wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key); 211e30331ffSRoss Zwisler } 212e30331ffSRoss Zwisler 213cfc93c6cSMatthew Wilcox /* 214cfc93c6cSMatthew Wilcox * Look up entry in page cache, wait for it to become unlocked if it 215cfc93c6cSMatthew Wilcox * is a DAX entry and return it. The caller must subsequently call 216cfc93c6cSMatthew Wilcox * put_unlocked_entry() if it did not lock the entry or dax_unlock_entry() 21723c84eb7SMatthew Wilcox (Oracle) * if it did. The entry returned may have a larger order than @order. 21823c84eb7SMatthew Wilcox (Oracle) * If @order is larger than the order of the entry found in i_pages, this 21923c84eb7SMatthew Wilcox (Oracle) * function returns a dax_is_conflict entry. 220cfc93c6cSMatthew Wilcox * 221cfc93c6cSMatthew Wilcox * Must be called with the i_pages lock held. 222cfc93c6cSMatthew Wilcox */ 22323c84eb7SMatthew Wilcox (Oracle) static void *get_unlocked_entry(struct xa_state *xas, unsigned int order) 224cfc93c6cSMatthew Wilcox { 225cfc93c6cSMatthew Wilcox void *entry; 226cfc93c6cSMatthew Wilcox struct wait_exceptional_entry_queue ewait; 227cfc93c6cSMatthew Wilcox wait_queue_head_t *wq; 228cfc93c6cSMatthew Wilcox 229cfc93c6cSMatthew Wilcox init_wait(&ewait.wait); 230cfc93c6cSMatthew Wilcox ewait.wait.func = wake_exceptional_entry_func; 231cfc93c6cSMatthew Wilcox 232cfc93c6cSMatthew Wilcox for (;;) { 2330e40de03SMatthew Wilcox entry = xas_find_conflict(xas); 2346370740eSDan Williams if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) 2356370740eSDan Williams return entry; 23623c84eb7SMatthew Wilcox (Oracle) if (dax_entry_order(entry) < order) 23723c84eb7SMatthew Wilcox (Oracle) return XA_RETRY_ENTRY; 2386370740eSDan Williams if (!dax_is_locked(entry)) 239cfc93c6cSMatthew Wilcox return entry; 240cfc93c6cSMatthew Wilcox 241b15cd800SMatthew Wilcox wq = dax_entry_waitqueue(xas, entry, &ewait.key); 242cfc93c6cSMatthew Wilcox prepare_to_wait_exclusive(wq, &ewait.wait, 243cfc93c6cSMatthew Wilcox TASK_UNINTERRUPTIBLE); 244cfc93c6cSMatthew Wilcox xas_unlock_irq(xas); 245cfc93c6cSMatthew Wilcox xas_reset(xas); 246cfc93c6cSMatthew Wilcox schedule(); 247cfc93c6cSMatthew Wilcox finish_wait(wq, &ewait.wait); 248cfc93c6cSMatthew Wilcox xas_lock_irq(xas); 249cfc93c6cSMatthew Wilcox } 250cfc93c6cSMatthew Wilcox } 251cfc93c6cSMatthew Wilcox 25255e56f06SMatthew Wilcox /* 25355e56f06SMatthew Wilcox * The only thing keeping the address space around is the i_pages lock 25455e56f06SMatthew Wilcox * (it's cycled in clear_inode() after removing the entries from i_pages) 25555e56f06SMatthew Wilcox * After we call xas_unlock_irq(), we cannot touch xas->xa. 25655e56f06SMatthew Wilcox */ 25755e56f06SMatthew Wilcox static void wait_entry_unlocked(struct xa_state *xas, void *entry) 25855e56f06SMatthew Wilcox { 25955e56f06SMatthew Wilcox struct wait_exceptional_entry_queue ewait; 26055e56f06SMatthew Wilcox wait_queue_head_t *wq; 26155e56f06SMatthew Wilcox 26255e56f06SMatthew Wilcox init_wait(&ewait.wait); 26355e56f06SMatthew Wilcox ewait.wait.func = wake_exceptional_entry_func; 26455e56f06SMatthew Wilcox 26555e56f06SMatthew Wilcox wq = dax_entry_waitqueue(xas, entry, &ewait.key); 266d8a70641SDan Williams /* 267d8a70641SDan Williams * Unlike get_unlocked_entry() there is no guarantee that this 268d8a70641SDan Williams * path ever successfully retrieves an unlocked entry before an 269d8a70641SDan Williams * inode dies. Perform a non-exclusive wait in case this path 270d8a70641SDan Williams * never successfully performs its own wake up. 271d8a70641SDan Williams */ 272d8a70641SDan Williams prepare_to_wait(wq, &ewait.wait, TASK_UNINTERRUPTIBLE); 27355e56f06SMatthew Wilcox xas_unlock_irq(xas); 27455e56f06SMatthew Wilcox schedule(); 27555e56f06SMatthew Wilcox finish_wait(wq, &ewait.wait); 27655e56f06SMatthew Wilcox } 27755e56f06SMatthew Wilcox 2784c3d043dSVivek Goyal static void put_unlocked_entry(struct xa_state *xas, void *entry, 2794c3d043dSVivek Goyal enum dax_wake_mode mode) 280cfc93c6cSMatthew Wilcox { 28161c30c98SJan Kara if (entry && !dax_is_conflict(entry)) 2824c3d043dSVivek Goyal dax_wake_entry(xas, entry, mode); 283cfc93c6cSMatthew Wilcox } 284cfc93c6cSMatthew Wilcox 285cfc93c6cSMatthew Wilcox /* 286cfc93c6cSMatthew Wilcox * We used the xa_state to get the entry, but then we locked the entry and 287cfc93c6cSMatthew Wilcox * dropped the xa_lock, so we know the xa_state is stale and must be reset 288cfc93c6cSMatthew Wilcox * before use. 289cfc93c6cSMatthew Wilcox */ 290cfc93c6cSMatthew Wilcox static void dax_unlock_entry(struct xa_state *xas, void *entry) 291cfc93c6cSMatthew Wilcox { 292cfc93c6cSMatthew Wilcox void *old; 293cfc93c6cSMatthew Wilcox 2947ae2ea7dSMatthew Wilcox BUG_ON(dax_is_locked(entry)); 295cfc93c6cSMatthew Wilcox xas_reset(xas); 296cfc93c6cSMatthew Wilcox xas_lock_irq(xas); 297cfc93c6cSMatthew Wilcox old = xas_store(xas, entry); 298cfc93c6cSMatthew Wilcox xas_unlock_irq(xas); 299cfc93c6cSMatthew Wilcox BUG_ON(!dax_is_locked(old)); 300698ab77aSVivek Goyal dax_wake_entry(xas, entry, WAKE_NEXT); 301cfc93c6cSMatthew Wilcox } 302cfc93c6cSMatthew Wilcox 303cfc93c6cSMatthew Wilcox /* 304cfc93c6cSMatthew Wilcox * Return: The entry stored at this location before it was locked. 305cfc93c6cSMatthew Wilcox */ 306cfc93c6cSMatthew Wilcox static void *dax_lock_entry(struct xa_state *xas, void *entry) 307cfc93c6cSMatthew Wilcox { 308cfc93c6cSMatthew Wilcox unsigned long v = xa_to_value(entry); 309cfc93c6cSMatthew Wilcox return xas_store(xas, xa_mk_value(v | DAX_LOCKED)); 310cfc93c6cSMatthew Wilcox } 311cfc93c6cSMatthew Wilcox 312d2c997c0SDan Williams static unsigned long dax_entry_size(void *entry) 313d2c997c0SDan Williams { 314d2c997c0SDan Williams if (dax_is_zero_entry(entry)) 315d2c997c0SDan Williams return 0; 316d2c997c0SDan Williams else if (dax_is_empty_entry(entry)) 317d2c997c0SDan Williams return 0; 318d2c997c0SDan Williams else if (dax_is_pmd_entry(entry)) 319d2c997c0SDan Williams return PMD_SIZE; 320d2c997c0SDan Williams else 321d2c997c0SDan Williams return PAGE_SIZE; 322d2c997c0SDan Williams } 323d2c997c0SDan Williams 324a77d19f4SMatthew Wilcox static unsigned long dax_end_pfn(void *entry) 325d2c997c0SDan Williams { 326a77d19f4SMatthew Wilcox return dax_to_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE; 327d2c997c0SDan Williams } 328d2c997c0SDan Williams 329d2c997c0SDan Williams /* 330d2c997c0SDan Williams * Iterate through all mapped pfns represented by an entry, i.e. skip 331d2c997c0SDan Williams * 'empty' and 'zero' entries. 332d2c997c0SDan Williams */ 333d2c997c0SDan Williams #define for_each_mapped_pfn(entry, pfn) \ 334a77d19f4SMatthew Wilcox for (pfn = dax_to_pfn(entry); \ 335a77d19f4SMatthew Wilcox pfn < dax_end_pfn(entry); pfn++) 336d2c997c0SDan Williams 3376061b69bSShiyang Ruan static inline bool dax_mapping_is_cow(struct address_space *mapping) 3386061b69bSShiyang Ruan { 3396061b69bSShiyang Ruan return (unsigned long)mapping == PAGE_MAPPING_DAX_COW; 3406061b69bSShiyang Ruan } 3416061b69bSShiyang Ruan 34273449dafSDan Williams /* 3436061b69bSShiyang Ruan * Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount. 3446061b69bSShiyang Ruan */ 3456061b69bSShiyang Ruan static inline void dax_mapping_set_cow(struct page *page) 3466061b69bSShiyang Ruan { 3476061b69bSShiyang Ruan if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) { 3486061b69bSShiyang Ruan /* 3496061b69bSShiyang Ruan * Reset the index if the page was already mapped 3506061b69bSShiyang Ruan * regularly before. 3516061b69bSShiyang Ruan */ 3526061b69bSShiyang Ruan if (page->mapping) 3536061b69bSShiyang Ruan page->index = 1; 3546061b69bSShiyang Ruan page->mapping = (void *)PAGE_MAPPING_DAX_COW; 3556061b69bSShiyang Ruan } 3566061b69bSShiyang Ruan page->index++; 3576061b69bSShiyang Ruan } 3586061b69bSShiyang Ruan 3596061b69bSShiyang Ruan /* 3606061b69bSShiyang Ruan * When it is called in dax_insert_entry(), the cow flag will indicate that 3616061b69bSShiyang Ruan * whether this entry is shared by multiple files. If so, set the page->mapping 3626061b69bSShiyang Ruan * FS_DAX_MAPPING_COW, and use page->index as refcount. 36373449dafSDan Williams */ 36473449dafSDan Williams static void dax_associate_entry(void *entry, struct address_space *mapping, 3656061b69bSShiyang Ruan struct vm_area_struct *vma, unsigned long address, bool cow) 366d2c997c0SDan Williams { 36773449dafSDan Williams unsigned long size = dax_entry_size(entry), pfn, index; 36873449dafSDan Williams int i = 0; 369d2c997c0SDan Williams 370d2c997c0SDan Williams if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) 371d2c997c0SDan Williams return; 372d2c997c0SDan Williams 37373449dafSDan Williams index = linear_page_index(vma, address & ~(size - 1)); 374d2c997c0SDan Williams for_each_mapped_pfn(entry, pfn) { 375d2c997c0SDan Williams struct page *page = pfn_to_page(pfn); 376d2c997c0SDan Williams 3776061b69bSShiyang Ruan if (cow) { 3786061b69bSShiyang Ruan dax_mapping_set_cow(page); 3796061b69bSShiyang Ruan } else { 380d2c997c0SDan Williams WARN_ON_ONCE(page->mapping); 381d2c997c0SDan Williams page->mapping = mapping; 38273449dafSDan Williams page->index = index + i++; 383d2c997c0SDan Williams } 384d2c997c0SDan Williams } 3856061b69bSShiyang Ruan } 386d2c997c0SDan Williams 387d2c997c0SDan Williams static void dax_disassociate_entry(void *entry, struct address_space *mapping, 388d2c997c0SDan Williams bool trunc) 389d2c997c0SDan Williams { 390d2c997c0SDan Williams unsigned long pfn; 391d2c997c0SDan Williams 392d2c997c0SDan Williams if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) 393d2c997c0SDan Williams return; 394d2c997c0SDan Williams 395d2c997c0SDan Williams for_each_mapped_pfn(entry, pfn) { 396d2c997c0SDan Williams struct page *page = pfn_to_page(pfn); 397d2c997c0SDan Williams 398d2c997c0SDan Williams WARN_ON_ONCE(trunc && page_ref_count(page) > 1); 3996061b69bSShiyang Ruan if (dax_mapping_is_cow(page->mapping)) { 4006061b69bSShiyang Ruan /* keep the CoW flag if this page is still shared */ 4016061b69bSShiyang Ruan if (page->index-- > 0) 4026061b69bSShiyang Ruan continue; 4036061b69bSShiyang Ruan } else 404d2c997c0SDan Williams WARN_ON_ONCE(page->mapping && page->mapping != mapping); 405d2c997c0SDan Williams page->mapping = NULL; 40673449dafSDan Williams page->index = 0; 407d2c997c0SDan Williams } 408d2c997c0SDan Williams } 409d2c997c0SDan Williams 4105fac7408SDan Williams static struct page *dax_busy_page(void *entry) 4115fac7408SDan Williams { 4125fac7408SDan Williams unsigned long pfn; 4135fac7408SDan Williams 4145fac7408SDan Williams for_each_mapped_pfn(entry, pfn) { 4155fac7408SDan Williams struct page *page = pfn_to_page(pfn); 4165fac7408SDan Williams 4175fac7408SDan Williams if (page_ref_count(page) > 1) 4185fac7408SDan Williams return page; 4195fac7408SDan Williams } 4205fac7408SDan Williams return NULL; 4215fac7408SDan Williams } 4225fac7408SDan Williams 423c5bbd451SMatthew Wilcox /* 424c2e8021aSShiyang Ruan * dax_lock_page - Lock the DAX entry corresponding to a page 425c5bbd451SMatthew Wilcox * @page: The page whose entry we want to lock 426c5bbd451SMatthew Wilcox * 427c5bbd451SMatthew Wilcox * Context: Process context. 42827359fd6SMatthew Wilcox * Return: A cookie to pass to dax_unlock_page() or 0 if the entry could 42927359fd6SMatthew Wilcox * not be locked. 430c5bbd451SMatthew Wilcox */ 43127359fd6SMatthew Wilcox dax_entry_t dax_lock_page(struct page *page) 432c2a7d2a1SDan Williams { 4339f32d221SMatthew Wilcox XA_STATE(xas, NULL, 0); 4349f32d221SMatthew Wilcox void *entry; 435c2a7d2a1SDan Williams 436c5bbd451SMatthew Wilcox /* Ensure page->mapping isn't freed while we look at it */ 437c5bbd451SMatthew Wilcox rcu_read_lock(); 438c2a7d2a1SDan Williams for (;;) { 4399f32d221SMatthew Wilcox struct address_space *mapping = READ_ONCE(page->mapping); 440c2a7d2a1SDan Williams 44127359fd6SMatthew Wilcox entry = NULL; 442c93db7bbSMatthew Wilcox if (!mapping || !dax_mapping(mapping)) 443c5bbd451SMatthew Wilcox break; 444c2a7d2a1SDan Williams 445c2a7d2a1SDan Williams /* 446c2a7d2a1SDan Williams * In the device-dax case there's no need to lock, a 447c2a7d2a1SDan Williams * struct dev_pagemap pin is sufficient to keep the 448c2a7d2a1SDan Williams * inode alive, and we assume we have dev_pagemap pin 449c2a7d2a1SDan Williams * otherwise we would not have a valid pfn_to_page() 450c2a7d2a1SDan Williams * translation. 451c2a7d2a1SDan Williams */ 45227359fd6SMatthew Wilcox entry = (void *)~0UL; 4539f32d221SMatthew Wilcox if (S_ISCHR(mapping->host->i_mode)) 454c5bbd451SMatthew Wilcox break; 455c2a7d2a1SDan Williams 4569f32d221SMatthew Wilcox xas.xa = &mapping->i_pages; 4579f32d221SMatthew Wilcox xas_lock_irq(&xas); 458c2a7d2a1SDan Williams if (mapping != page->mapping) { 4599f32d221SMatthew Wilcox xas_unlock_irq(&xas); 460c2a7d2a1SDan Williams continue; 461c2a7d2a1SDan Williams } 4629f32d221SMatthew Wilcox xas_set(&xas, page->index); 4639f32d221SMatthew Wilcox entry = xas_load(&xas); 4649f32d221SMatthew Wilcox if (dax_is_locked(entry)) { 465c5bbd451SMatthew Wilcox rcu_read_unlock(); 46655e56f06SMatthew Wilcox wait_entry_unlocked(&xas, entry); 467c5bbd451SMatthew Wilcox rcu_read_lock(); 468c2a7d2a1SDan Williams continue; 469c2a7d2a1SDan Williams } 4709f32d221SMatthew Wilcox dax_lock_entry(&xas, entry); 4719f32d221SMatthew Wilcox xas_unlock_irq(&xas); 472c5bbd451SMatthew Wilcox break; 4739f32d221SMatthew Wilcox } 474c5bbd451SMatthew Wilcox rcu_read_unlock(); 47527359fd6SMatthew Wilcox return (dax_entry_t)entry; 476c2a7d2a1SDan Williams } 477c2a7d2a1SDan Williams 47827359fd6SMatthew Wilcox void dax_unlock_page(struct page *page, dax_entry_t cookie) 479c2a7d2a1SDan Williams { 480c2a7d2a1SDan Williams struct address_space *mapping = page->mapping; 4819f32d221SMatthew Wilcox XA_STATE(xas, &mapping->i_pages, page->index); 482c2a7d2a1SDan Williams 4839f32d221SMatthew Wilcox if (S_ISCHR(mapping->host->i_mode)) 484c2a7d2a1SDan Williams return; 485c2a7d2a1SDan Williams 48627359fd6SMatthew Wilcox dax_unlock_entry(&xas, (void *)cookie); 487c2a7d2a1SDan Williams } 488c2a7d2a1SDan Williams 489ac401cc7SJan Kara /* 4902f437effSShiyang Ruan * dax_lock_mapping_entry - Lock the DAX entry corresponding to a mapping 4912f437effSShiyang Ruan * @mapping: the file's mapping whose entry we want to lock 4922f437effSShiyang Ruan * @index: the offset within this file 4932f437effSShiyang Ruan * @page: output the dax page corresponding to this dax entry 4942f437effSShiyang Ruan * 4952f437effSShiyang Ruan * Return: A cookie to pass to dax_unlock_mapping_entry() or 0 if the entry 4962f437effSShiyang Ruan * could not be locked. 4972f437effSShiyang Ruan */ 4982f437effSShiyang Ruan dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, pgoff_t index, 4992f437effSShiyang Ruan struct page **page) 5002f437effSShiyang Ruan { 5012f437effSShiyang Ruan XA_STATE(xas, NULL, 0); 5022f437effSShiyang Ruan void *entry; 5032f437effSShiyang Ruan 5042f437effSShiyang Ruan rcu_read_lock(); 5052f437effSShiyang Ruan for (;;) { 5062f437effSShiyang Ruan entry = NULL; 5072f437effSShiyang Ruan if (!dax_mapping(mapping)) 5082f437effSShiyang Ruan break; 5092f437effSShiyang Ruan 5102f437effSShiyang Ruan xas.xa = &mapping->i_pages; 5112f437effSShiyang Ruan xas_lock_irq(&xas); 5122f437effSShiyang Ruan xas_set(&xas, index); 5132f437effSShiyang Ruan entry = xas_load(&xas); 5142f437effSShiyang Ruan if (dax_is_locked(entry)) { 5152f437effSShiyang Ruan rcu_read_unlock(); 5162f437effSShiyang Ruan wait_entry_unlocked(&xas, entry); 5172f437effSShiyang Ruan rcu_read_lock(); 5182f437effSShiyang Ruan continue; 5192f437effSShiyang Ruan } 5202f437effSShiyang Ruan if (!entry || 5212f437effSShiyang Ruan dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { 5222f437effSShiyang Ruan /* 5232f437effSShiyang Ruan * Because we are looking for entry from file's mapping 5242f437effSShiyang Ruan * and index, so the entry may not be inserted for now, 5252f437effSShiyang Ruan * or even a zero/empty entry. We don't think this is 5262f437effSShiyang Ruan * an error case. So, return a special value and do 5272f437effSShiyang Ruan * not output @page. 5282f437effSShiyang Ruan */ 5292f437effSShiyang Ruan entry = (void *)~0UL; 5302f437effSShiyang Ruan } else { 5312f437effSShiyang Ruan *page = pfn_to_page(dax_to_pfn(entry)); 5322f437effSShiyang Ruan dax_lock_entry(&xas, entry); 5332f437effSShiyang Ruan } 5342f437effSShiyang Ruan xas_unlock_irq(&xas); 5352f437effSShiyang Ruan break; 5362f437effSShiyang Ruan } 5372f437effSShiyang Ruan rcu_read_unlock(); 5382f437effSShiyang Ruan return (dax_entry_t)entry; 5392f437effSShiyang Ruan } 5402f437effSShiyang Ruan 5412f437effSShiyang Ruan void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index, 5422f437effSShiyang Ruan dax_entry_t cookie) 5432f437effSShiyang Ruan { 5442f437effSShiyang Ruan XA_STATE(xas, &mapping->i_pages, index); 5452f437effSShiyang Ruan 5462f437effSShiyang Ruan if (cookie == ~0UL) 5472f437effSShiyang Ruan return; 5482f437effSShiyang Ruan 5492f437effSShiyang Ruan dax_unlock_entry(&xas, (void *)cookie); 5502f437effSShiyang Ruan } 5512f437effSShiyang Ruan 5522f437effSShiyang Ruan /* 553a77d19f4SMatthew Wilcox * Find page cache entry at given index. If it is a DAX entry, return it 554a77d19f4SMatthew Wilcox * with the entry locked. If the page cache doesn't contain an entry at 555a77d19f4SMatthew Wilcox * that index, add a locked empty entry. 556ac401cc7SJan Kara * 5573159f943SMatthew Wilcox * When requesting an entry with size DAX_PMD, grab_mapping_entry() will 558b15cd800SMatthew Wilcox * either return that locked entry or will return VM_FAULT_FALLBACK. 559b15cd800SMatthew Wilcox * This will happen if there are any PTE entries within the PMD range 560b15cd800SMatthew Wilcox * that we are requesting. 561642261acSRoss Zwisler * 562b15cd800SMatthew Wilcox * We always favor PTE entries over PMD entries. There isn't a flow where we 563b15cd800SMatthew Wilcox * evict PTE entries in order to 'upgrade' them to a PMD entry. A PMD 564b15cd800SMatthew Wilcox * insertion will fail if it finds any PTE entries already in the tree, and a 565b15cd800SMatthew Wilcox * PTE insertion will cause an existing PMD entry to be unmapped and 566b15cd800SMatthew Wilcox * downgraded to PTE entries. This happens for both PMD zero pages as 567b15cd800SMatthew Wilcox * well as PMD empty entries. 568642261acSRoss Zwisler * 569b15cd800SMatthew Wilcox * The exception to this downgrade path is for PMD entries that have 570b15cd800SMatthew Wilcox * real storage backing them. We will leave these real PMD entries in 571b15cd800SMatthew Wilcox * the tree, and PTE writes will simply dirty the entire PMD entry. 572642261acSRoss Zwisler * 573ac401cc7SJan Kara * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For 574ac401cc7SJan Kara * persistent memory the benefit is doubtful. We can add that later if we can 575ac401cc7SJan Kara * show it helps. 576b15cd800SMatthew Wilcox * 577b15cd800SMatthew Wilcox * On error, this function does not return an ERR_PTR. Instead it returns 578b15cd800SMatthew Wilcox * a VM_FAULT code, encoded as an xarray internal entry. The ERR_PTR values 579b15cd800SMatthew Wilcox * overlap with xarray value entries. 580ac401cc7SJan Kara */ 581b15cd800SMatthew Wilcox static void *grab_mapping_entry(struct xa_state *xas, 58223c84eb7SMatthew Wilcox (Oracle) struct address_space *mapping, unsigned int order) 583ac401cc7SJan Kara { 584b15cd800SMatthew Wilcox unsigned long index = xas->xa_index; 5851a14e377SJan Kara bool pmd_downgrade; /* splitting PMD entry into PTE entries? */ 586b15cd800SMatthew Wilcox void *entry; 587ac401cc7SJan Kara 588b15cd800SMatthew Wilcox retry: 5891a14e377SJan Kara pmd_downgrade = false; 590b15cd800SMatthew Wilcox xas_lock_irq(xas); 59123c84eb7SMatthew Wilcox (Oracle) entry = get_unlocked_entry(xas, order); 592642261acSRoss Zwisler 593b15cd800SMatthew Wilcox if (entry) { 59423c84eb7SMatthew Wilcox (Oracle) if (dax_is_conflict(entry)) 59523c84eb7SMatthew Wilcox (Oracle) goto fallback; 5960e40de03SMatthew Wilcox if (!xa_is_value(entry)) { 59749688e65SHao Li xas_set_err(xas, -EIO); 59891d25ba8SRoss Zwisler goto out_unlock; 59991d25ba8SRoss Zwisler } 60091d25ba8SRoss Zwisler 60123c84eb7SMatthew Wilcox (Oracle) if (order == 0) { 60291d25ba8SRoss Zwisler if (dax_is_pmd_entry(entry) && 603642261acSRoss Zwisler (dax_is_zero_entry(entry) || 604642261acSRoss Zwisler dax_is_empty_entry(entry))) { 605642261acSRoss Zwisler pmd_downgrade = true; 606642261acSRoss Zwisler } 607642261acSRoss Zwisler } 608642261acSRoss Zwisler } 609642261acSRoss Zwisler 610642261acSRoss Zwisler if (pmd_downgrade) { 611642261acSRoss Zwisler /* 612642261acSRoss Zwisler * Make sure 'entry' remains valid while we drop 613b93b0163SMatthew Wilcox * the i_pages lock. 614642261acSRoss Zwisler */ 615b15cd800SMatthew Wilcox dax_lock_entry(xas, entry); 616642261acSRoss Zwisler 617642261acSRoss Zwisler /* 618642261acSRoss Zwisler * Besides huge zero pages the only other thing that gets 619642261acSRoss Zwisler * downgraded are empty entries which don't need to be 620642261acSRoss Zwisler * unmapped. 621642261acSRoss Zwisler */ 622b15cd800SMatthew Wilcox if (dax_is_zero_entry(entry)) { 623b15cd800SMatthew Wilcox xas_unlock_irq(xas); 624b15cd800SMatthew Wilcox unmap_mapping_pages(mapping, 625b15cd800SMatthew Wilcox xas->xa_index & ~PG_PMD_COLOUR, 626977fbdcdSMatthew Wilcox PG_PMD_NR, false); 627b15cd800SMatthew Wilcox xas_reset(xas); 628b15cd800SMatthew Wilcox xas_lock_irq(xas); 629e11f8b7bSRoss Zwisler } 630e11f8b7bSRoss Zwisler 631d2c997c0SDan Williams dax_disassociate_entry(entry, mapping, false); 632b15cd800SMatthew Wilcox xas_store(xas, NULL); /* undo the PMD join */ 633698ab77aSVivek Goyal dax_wake_entry(xas, entry, WAKE_ALL); 6347f0e07fbSMatthew Wilcox (Oracle) mapping->nrpages -= PG_PMD_NR; 635b15cd800SMatthew Wilcox entry = NULL; 636b15cd800SMatthew Wilcox xas_set(xas, index); 637642261acSRoss Zwisler } 638642261acSRoss Zwisler 639b15cd800SMatthew Wilcox if (entry) { 640b15cd800SMatthew Wilcox dax_lock_entry(xas, entry); 641b15cd800SMatthew Wilcox } else { 64223c84eb7SMatthew Wilcox (Oracle) unsigned long flags = DAX_EMPTY; 64323c84eb7SMatthew Wilcox (Oracle) 64423c84eb7SMatthew Wilcox (Oracle) if (order > 0) 64523c84eb7SMatthew Wilcox (Oracle) flags |= DAX_PMD; 64623c84eb7SMatthew Wilcox (Oracle) entry = dax_make_entry(pfn_to_pfn_t(0), flags); 647b15cd800SMatthew Wilcox dax_lock_entry(xas, entry); 648b15cd800SMatthew Wilcox if (xas_error(xas)) 649b15cd800SMatthew Wilcox goto out_unlock; 6507f0e07fbSMatthew Wilcox (Oracle) mapping->nrpages += 1UL << order; 651ac401cc7SJan Kara } 652b15cd800SMatthew Wilcox 653642261acSRoss Zwisler out_unlock: 654b15cd800SMatthew Wilcox xas_unlock_irq(xas); 655b15cd800SMatthew Wilcox if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM)) 656b15cd800SMatthew Wilcox goto retry; 657b15cd800SMatthew Wilcox if (xas->xa_node == XA_ERROR(-ENOMEM)) 658b15cd800SMatthew Wilcox return xa_mk_internal(VM_FAULT_OOM); 659b15cd800SMatthew Wilcox if (xas_error(xas)) 660b15cd800SMatthew Wilcox return xa_mk_internal(VM_FAULT_SIGBUS); 661e3ad61c6SRoss Zwisler return entry; 662b15cd800SMatthew Wilcox fallback: 663b15cd800SMatthew Wilcox xas_unlock_irq(xas); 664b15cd800SMatthew Wilcox return xa_mk_internal(VM_FAULT_FALLBACK); 665ac401cc7SJan Kara } 666ac401cc7SJan Kara 6675fac7408SDan Williams /** 6686bbdd563SVivek Goyal * dax_layout_busy_page_range - find first pinned page in @mapping 6695fac7408SDan Williams * @mapping: address space to scan for a page with ref count > 1 6706bbdd563SVivek Goyal * @start: Starting offset. Page containing 'start' is included. 6716bbdd563SVivek Goyal * @end: End offset. Page containing 'end' is included. If 'end' is LLONG_MAX, 6726bbdd563SVivek Goyal * pages from 'start' till the end of file are included. 6735fac7408SDan Williams * 6745fac7408SDan Williams * DAX requires ZONE_DEVICE mapped pages. These pages are never 6755fac7408SDan Williams * 'onlined' to the page allocator so they are considered idle when 6765fac7408SDan Williams * page->count == 1. A filesystem uses this interface to determine if 6775fac7408SDan Williams * any page in the mapping is busy, i.e. for DMA, or other 6785fac7408SDan Williams * get_user_pages() usages. 6795fac7408SDan Williams * 6805fac7408SDan Williams * It is expected that the filesystem is holding locks to block the 6815fac7408SDan Williams * establishment of new mappings in this address_space. I.e. it expects 6825fac7408SDan Williams * to be able to run unmap_mapping_range() and subsequently not race 6835fac7408SDan Williams * mapping_mapped() becoming true. 6845fac7408SDan Williams */ 6856bbdd563SVivek Goyal struct page *dax_layout_busy_page_range(struct address_space *mapping, 6866bbdd563SVivek Goyal loff_t start, loff_t end) 6875fac7408SDan Williams { 688084a8990SMatthew Wilcox void *entry; 689084a8990SMatthew Wilcox unsigned int scanned = 0; 6905fac7408SDan Williams struct page *page = NULL; 6916bbdd563SVivek Goyal pgoff_t start_idx = start >> PAGE_SHIFT; 6926bbdd563SVivek Goyal pgoff_t end_idx; 6936bbdd563SVivek Goyal XA_STATE(xas, &mapping->i_pages, start_idx); 6945fac7408SDan Williams 6955fac7408SDan Williams /* 6965fac7408SDan Williams * In the 'limited' case get_user_pages() for dax is disabled. 6975fac7408SDan Williams */ 6985fac7408SDan Williams if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) 6995fac7408SDan Williams return NULL; 7005fac7408SDan Williams 7015fac7408SDan Williams if (!dax_mapping(mapping) || !mapping_mapped(mapping)) 7025fac7408SDan Williams return NULL; 7035fac7408SDan Williams 7046bbdd563SVivek Goyal /* If end == LLONG_MAX, all pages from start to till end of file */ 7056bbdd563SVivek Goyal if (end == LLONG_MAX) 7066bbdd563SVivek Goyal end_idx = ULONG_MAX; 7076bbdd563SVivek Goyal else 7086bbdd563SVivek Goyal end_idx = end >> PAGE_SHIFT; 7095fac7408SDan Williams /* 7105fac7408SDan Williams * If we race get_user_pages_fast() here either we'll see the 711084a8990SMatthew Wilcox * elevated page count in the iteration and wait, or 7125fac7408SDan Williams * get_user_pages_fast() will see that the page it took a reference 7135fac7408SDan Williams * against is no longer mapped in the page tables and bail to the 7145fac7408SDan Williams * get_user_pages() slow path. The slow path is protected by 7155fac7408SDan Williams * pte_lock() and pmd_lock(). New references are not taken without 7166bbdd563SVivek Goyal * holding those locks, and unmap_mapping_pages() will not zero the 7175fac7408SDan Williams * pte or pmd without holding the respective lock, so we are 7185fac7408SDan Williams * guaranteed to either see new references or prevent new 7195fac7408SDan Williams * references from being established. 7205fac7408SDan Williams */ 7216bbdd563SVivek Goyal unmap_mapping_pages(mapping, start_idx, end_idx - start_idx + 1, 0); 7225fac7408SDan Williams 723084a8990SMatthew Wilcox xas_lock_irq(&xas); 7246bbdd563SVivek Goyal xas_for_each(&xas, entry, end_idx) { 725084a8990SMatthew Wilcox if (WARN_ON_ONCE(!xa_is_value(entry))) 7265fac7408SDan Williams continue; 727084a8990SMatthew Wilcox if (unlikely(dax_is_locked(entry))) 72823c84eb7SMatthew Wilcox (Oracle) entry = get_unlocked_entry(&xas, 0); 7295fac7408SDan Williams if (entry) 7305fac7408SDan Williams page = dax_busy_page(entry); 7314c3d043dSVivek Goyal put_unlocked_entry(&xas, entry, WAKE_NEXT); 7325fac7408SDan Williams if (page) 7335fac7408SDan Williams break; 734084a8990SMatthew Wilcox if (++scanned % XA_CHECK_SCHED) 735084a8990SMatthew Wilcox continue; 736cdbf8897SRoss Zwisler 737084a8990SMatthew Wilcox xas_pause(&xas); 738084a8990SMatthew Wilcox xas_unlock_irq(&xas); 739084a8990SMatthew Wilcox cond_resched(); 740084a8990SMatthew Wilcox xas_lock_irq(&xas); 7415fac7408SDan Williams } 742084a8990SMatthew Wilcox xas_unlock_irq(&xas); 7435fac7408SDan Williams return page; 7445fac7408SDan Williams } 7456bbdd563SVivek Goyal EXPORT_SYMBOL_GPL(dax_layout_busy_page_range); 7466bbdd563SVivek Goyal 7476bbdd563SVivek Goyal struct page *dax_layout_busy_page(struct address_space *mapping) 7486bbdd563SVivek Goyal { 7496bbdd563SVivek Goyal return dax_layout_busy_page_range(mapping, 0, LLONG_MAX); 7506bbdd563SVivek Goyal } 7515fac7408SDan Williams EXPORT_SYMBOL_GPL(dax_layout_busy_page); 7525fac7408SDan Williams 753a77d19f4SMatthew Wilcox static int __dax_invalidate_entry(struct address_space *mapping, 754c6dcf52cSJan Kara pgoff_t index, bool trunc) 755c6dcf52cSJan Kara { 75607f2d89cSMatthew Wilcox XA_STATE(xas, &mapping->i_pages, index); 757c6dcf52cSJan Kara int ret = 0; 758c6dcf52cSJan Kara void *entry; 759c6dcf52cSJan Kara 76007f2d89cSMatthew Wilcox xas_lock_irq(&xas); 76123c84eb7SMatthew Wilcox (Oracle) entry = get_unlocked_entry(&xas, 0); 7623159f943SMatthew Wilcox if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) 763c6dcf52cSJan Kara goto out; 764c6dcf52cSJan Kara if (!trunc && 76507f2d89cSMatthew Wilcox (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY) || 76607f2d89cSMatthew Wilcox xas_get_mark(&xas, PAGECACHE_TAG_TOWRITE))) 767c6dcf52cSJan Kara goto out; 768d2c997c0SDan Williams dax_disassociate_entry(entry, mapping, trunc); 76907f2d89cSMatthew Wilcox xas_store(&xas, NULL); 7707f0e07fbSMatthew Wilcox (Oracle) mapping->nrpages -= 1UL << dax_entry_order(entry); 771c6dcf52cSJan Kara ret = 1; 772c6dcf52cSJan Kara out: 77323738832SVivek Goyal put_unlocked_entry(&xas, entry, WAKE_ALL); 77407f2d89cSMatthew Wilcox xas_unlock_irq(&xas); 775c6dcf52cSJan Kara return ret; 776c6dcf52cSJan Kara } 77707f2d89cSMatthew Wilcox 778ac401cc7SJan Kara /* 7793159f943SMatthew Wilcox * Delete DAX entry at @index from @mapping. Wait for it 7803159f943SMatthew Wilcox * to be unlocked before deleting it. 781ac401cc7SJan Kara */ 782ac401cc7SJan Kara int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index) 783ac401cc7SJan Kara { 784a77d19f4SMatthew Wilcox int ret = __dax_invalidate_entry(mapping, index, true); 785ac401cc7SJan Kara 786ac401cc7SJan Kara /* 787ac401cc7SJan Kara * This gets called from truncate / punch_hole path. As such, the caller 788ac401cc7SJan Kara * must hold locks protecting against concurrent modifications of the 789a77d19f4SMatthew Wilcox * page cache (usually fs-private i_mmap_sem for writing). Since the 7903159f943SMatthew Wilcox * caller has seen a DAX entry for this index, we better find it 791ac401cc7SJan Kara * at that index as well... 792ac401cc7SJan Kara */ 793c6dcf52cSJan Kara WARN_ON_ONCE(!ret); 794c6dcf52cSJan Kara return ret; 795ac401cc7SJan Kara } 796ac401cc7SJan Kara 797c6dcf52cSJan Kara /* 7983159f943SMatthew Wilcox * Invalidate DAX entry if it is clean. 799c6dcf52cSJan Kara */ 800c6dcf52cSJan Kara int dax_invalidate_mapping_entry_sync(struct address_space *mapping, 801c6dcf52cSJan Kara pgoff_t index) 802c6dcf52cSJan Kara { 803a77d19f4SMatthew Wilcox return __dax_invalidate_entry(mapping, index, false); 804ac401cc7SJan Kara } 805ac401cc7SJan Kara 80660696eb2SChristoph Hellwig static pgoff_t dax_iomap_pgoff(const struct iomap *iomap, loff_t pos) 807f7ca90b1SMatthew Wilcox { 808de205114SChristoph Hellwig return PHYS_PFN(iomap->addr + (pos & PAGE_MASK) - iomap->offset); 809429f8de7SChristoph Hellwig } 810429f8de7SChristoph Hellwig 811429f8de7SChristoph Hellwig static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter) 812429f8de7SChristoph Hellwig { 81360696eb2SChristoph Hellwig pgoff_t pgoff = dax_iomap_pgoff(&iter->iomap, iter->pos); 814cccbce67SDan Williams void *vto, *kaddr; 815cccbce67SDan Williams long rc; 816cccbce67SDan Williams int id; 817e2e05394SRoss Zwisler 818cccbce67SDan Williams id = dax_read_lock(); 819e511c4a3SJane Chu rc = dax_direct_access(iter->iomap.dax_dev, pgoff, 1, DAX_ACCESS, 820e511c4a3SJane Chu &kaddr, NULL); 821cccbce67SDan Williams if (rc < 0) { 822cccbce67SDan Williams dax_read_unlock(id); 823cccbce67SDan Williams return rc; 824cccbce67SDan Williams } 825429f8de7SChristoph Hellwig vto = kmap_atomic(vmf->cow_page); 826429f8de7SChristoph Hellwig copy_user_page(vto, kaddr, vmf->address, vmf->cow_page); 827f7ca90b1SMatthew Wilcox kunmap_atomic(vto); 828cccbce67SDan Williams dax_read_unlock(id); 829f7ca90b1SMatthew Wilcox return 0; 830f7ca90b1SMatthew Wilcox } 831f7ca90b1SMatthew Wilcox 832642261acSRoss Zwisler /* 833*e5d6df73SShiyang Ruan * MAP_SYNC on a dax mapping guarantees dirty metadata is 834*e5d6df73SShiyang Ruan * flushed on write-faults (non-cow), but not read-faults. 835*e5d6df73SShiyang Ruan */ 836*e5d6df73SShiyang Ruan static bool dax_fault_is_synchronous(const struct iomap_iter *iter, 837*e5d6df73SShiyang Ruan struct vm_area_struct *vma) 838*e5d6df73SShiyang Ruan { 839*e5d6df73SShiyang Ruan return (iter->flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC) && 840*e5d6df73SShiyang Ruan (iter->iomap.flags & IOMAP_F_DIRTY); 841*e5d6df73SShiyang Ruan } 842*e5d6df73SShiyang Ruan 843*e5d6df73SShiyang Ruan static bool dax_fault_is_cow(const struct iomap_iter *iter) 844*e5d6df73SShiyang Ruan { 845*e5d6df73SShiyang Ruan return (iter->flags & IOMAP_WRITE) && 846*e5d6df73SShiyang Ruan (iter->iomap.flags & IOMAP_F_SHARED); 847*e5d6df73SShiyang Ruan } 848*e5d6df73SShiyang Ruan 849*e5d6df73SShiyang Ruan /* 850642261acSRoss Zwisler * By this point grab_mapping_entry() has ensured that we have a locked entry 851642261acSRoss Zwisler * of the appropriate size so we don't have to worry about downgrading PMDs to 852642261acSRoss Zwisler * PTEs. If we happen to be trying to insert a PTE and there is a PMD 853642261acSRoss Zwisler * already in the tree, we will skip the insertion and just dirty the PMD as 854642261acSRoss Zwisler * appropriate. 855642261acSRoss Zwisler */ 856*e5d6df73SShiyang Ruan static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, 857*e5d6df73SShiyang Ruan const struct iomap_iter *iter, void *entry, pfn_t pfn, 858*e5d6df73SShiyang Ruan unsigned long flags) 8599973c98eSRoss Zwisler { 860*e5d6df73SShiyang Ruan struct address_space *mapping = vmf->vma->vm_file->f_mapping; 861b15cd800SMatthew Wilcox void *new_entry = dax_make_entry(pfn, flags); 862*e5d6df73SShiyang Ruan bool dirty = !dax_fault_is_synchronous(iter, vmf->vma); 863*e5d6df73SShiyang Ruan bool cow = dax_fault_is_cow(iter); 8649973c98eSRoss Zwisler 865f5b7b748SJan Kara if (dirty) 8669973c98eSRoss Zwisler __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); 8679973c98eSRoss Zwisler 868*e5d6df73SShiyang Ruan if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) { 869b15cd800SMatthew Wilcox unsigned long index = xas->xa_index; 87091d25ba8SRoss Zwisler /* we are replacing a zero page with block mapping */ 87191d25ba8SRoss Zwisler if (dax_is_pmd_entry(entry)) 872977fbdcdSMatthew Wilcox unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR, 873977fbdcdSMatthew Wilcox PG_PMD_NR, false); 87491d25ba8SRoss Zwisler else /* pte entry */ 875b15cd800SMatthew Wilcox unmap_mapping_pages(mapping, index, 1, false); 876ac401cc7SJan Kara } 8779973c98eSRoss Zwisler 878b15cd800SMatthew Wilcox xas_reset(xas); 879b15cd800SMatthew Wilcox xas_lock_irq(xas); 880*e5d6df73SShiyang Ruan if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { 8811571c029SJan Kara void *old; 8821571c029SJan Kara 883d2c997c0SDan Williams dax_disassociate_entry(entry, mapping, false); 8846061b69bSShiyang Ruan dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address, 885*e5d6df73SShiyang Ruan cow); 886642261acSRoss Zwisler /* 887a77d19f4SMatthew Wilcox * Only swap our new entry into the page cache if the current 888642261acSRoss Zwisler * entry is a zero page or an empty entry. If a normal PTE or 889a77d19f4SMatthew Wilcox * PMD entry is already in the cache, we leave it alone. This 890642261acSRoss Zwisler * means that if we are trying to insert a PTE and the 891642261acSRoss Zwisler * existing entry is a PMD, we will just leave the PMD in the 892642261acSRoss Zwisler * tree and dirty it if necessary. 893642261acSRoss Zwisler */ 8941571c029SJan Kara old = dax_lock_entry(xas, new_entry); 895b15cd800SMatthew Wilcox WARN_ON_ONCE(old != xa_mk_value(xa_to_value(entry) | 896b15cd800SMatthew Wilcox DAX_LOCKED)); 89791d25ba8SRoss Zwisler entry = new_entry; 898b15cd800SMatthew Wilcox } else { 899b15cd800SMatthew Wilcox xas_load(xas); /* Walk the xa_state */ 900ac401cc7SJan Kara } 90191d25ba8SRoss Zwisler 902f5b7b748SJan Kara if (dirty) 903b15cd800SMatthew Wilcox xas_set_mark(xas, PAGECACHE_TAG_DIRTY); 90491d25ba8SRoss Zwisler 905*e5d6df73SShiyang Ruan if (cow) 906*e5d6df73SShiyang Ruan xas_set_mark(xas, PAGECACHE_TAG_TOWRITE); 907*e5d6df73SShiyang Ruan 908b15cd800SMatthew Wilcox xas_unlock_irq(xas); 90991d25ba8SRoss Zwisler return entry; 9109973c98eSRoss Zwisler } 9119973c98eSRoss Zwisler 9129fc747f6SMatthew Wilcox static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, 9139fc747f6SMatthew Wilcox struct address_space *mapping, void *entry) 9149973c98eSRoss Zwisler { 91506083a09SMuchun Song unsigned long pfn, index, count, end; 9163fe0791cSDan Williams long ret = 0; 91706083a09SMuchun Song struct vm_area_struct *vma; 9189973c98eSRoss Zwisler 9199973c98eSRoss Zwisler /* 920a6abc2c0SJan Kara * A page got tagged dirty in DAX mapping? Something is seriously 921a6abc2c0SJan Kara * wrong. 9229973c98eSRoss Zwisler */ 9233159f943SMatthew Wilcox if (WARN_ON(!xa_is_value(entry))) 924a6abc2c0SJan Kara return -EIO; 9259973c98eSRoss Zwisler 9269fc747f6SMatthew Wilcox if (unlikely(dax_is_locked(entry))) { 9279fc747f6SMatthew Wilcox void *old_entry = entry; 9289fc747f6SMatthew Wilcox 92923c84eb7SMatthew Wilcox (Oracle) entry = get_unlocked_entry(xas, 0); 9309fc747f6SMatthew Wilcox 931a6abc2c0SJan Kara /* Entry got punched out / reallocated? */ 9329fc747f6SMatthew Wilcox if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) 933a6abc2c0SJan Kara goto put_unlocked; 934a6abc2c0SJan Kara /* 9359fc747f6SMatthew Wilcox * Entry got reallocated elsewhere? No need to writeback. 9369fc747f6SMatthew Wilcox * We have to compare pfns as we must not bail out due to 9379fc747f6SMatthew Wilcox * difference in lockbit or entry type. 938a6abc2c0SJan Kara */ 9399fc747f6SMatthew Wilcox if (dax_to_pfn(old_entry) != dax_to_pfn(entry)) 940a6abc2c0SJan Kara goto put_unlocked; 941642261acSRoss Zwisler if (WARN_ON_ONCE(dax_is_empty_entry(entry) || 942642261acSRoss Zwisler dax_is_zero_entry(entry))) { 9439973c98eSRoss Zwisler ret = -EIO; 944a6abc2c0SJan Kara goto put_unlocked; 9459973c98eSRoss Zwisler } 9469973c98eSRoss Zwisler 9479fc747f6SMatthew Wilcox /* Another fsync thread may have already done this entry */ 9489fc747f6SMatthew Wilcox if (!xas_get_mark(xas, PAGECACHE_TAG_TOWRITE)) 949a6abc2c0SJan Kara goto put_unlocked; 9509fc747f6SMatthew Wilcox } 9519fc747f6SMatthew Wilcox 952a6abc2c0SJan Kara /* Lock the entry to serialize with page faults */ 9539fc747f6SMatthew Wilcox dax_lock_entry(xas, entry); 9549fc747f6SMatthew Wilcox 955a6abc2c0SJan Kara /* 956a6abc2c0SJan Kara * We can clear the tag now but we have to be careful so that concurrent 957a6abc2c0SJan Kara * dax_writeback_one() calls for the same index cannot finish before we 958a6abc2c0SJan Kara * actually flush the caches. This is achieved as the calls will look 959b93b0163SMatthew Wilcox * at the entry only under the i_pages lock and once they do that 960b93b0163SMatthew Wilcox * they will see the entry locked and wait for it to unlock. 961a6abc2c0SJan Kara */ 9629fc747f6SMatthew Wilcox xas_clear_mark(xas, PAGECACHE_TAG_TOWRITE); 9639fc747f6SMatthew Wilcox xas_unlock_irq(xas); 964a6abc2c0SJan Kara 965642261acSRoss Zwisler /* 966e4b3448bSMatthew Wilcox * If dax_writeback_mapping_range() was given a wbc->range_start 967e4b3448bSMatthew Wilcox * in the middle of a PMD, the 'index' we use needs to be 968e4b3448bSMatthew Wilcox * aligned to the start of the PMD. 9693fe0791cSDan Williams * This allows us to flush for PMD_SIZE and not have to worry about 9703fe0791cSDan Williams * partial PMD writebacks. 971642261acSRoss Zwisler */ 972a77d19f4SMatthew Wilcox pfn = dax_to_pfn(entry); 973e4b3448bSMatthew Wilcox count = 1UL << dax_entry_order(entry); 974e4b3448bSMatthew Wilcox index = xas->xa_index & ~(count - 1); 97506083a09SMuchun Song end = index + count - 1; 976cccbce67SDan Williams 97706083a09SMuchun Song /* Walk all mappings of a given index of a file and writeprotect them */ 97806083a09SMuchun Song i_mmap_lock_read(mapping); 97906083a09SMuchun Song vma_interval_tree_foreach(vma, &mapping->i_mmap, index, end) { 98006083a09SMuchun Song pfn_mkclean_range(pfn, count, index, vma); 98106083a09SMuchun Song cond_resched(); 98206083a09SMuchun Song } 98306083a09SMuchun Song i_mmap_unlock_read(mapping); 98406083a09SMuchun Song 985e4b3448bSMatthew Wilcox dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE); 9864b4bb46dSJan Kara /* 9874b4bb46dSJan Kara * After we have flushed the cache, we can clear the dirty tag. There 9884b4bb46dSJan Kara * cannot be new dirty data in the pfn after the flush has completed as 9894b4bb46dSJan Kara * the pfn mappings are writeprotected and fault waits for mapping 9904b4bb46dSJan Kara * entry lock. 9914b4bb46dSJan Kara */ 9929fc747f6SMatthew Wilcox xas_reset(xas); 9939fc747f6SMatthew Wilcox xas_lock_irq(xas); 9949fc747f6SMatthew Wilcox xas_store(xas, entry); 9959fc747f6SMatthew Wilcox xas_clear_mark(xas, PAGECACHE_TAG_DIRTY); 996698ab77aSVivek Goyal dax_wake_entry(xas, entry, WAKE_NEXT); 9979fc747f6SMatthew Wilcox 998e4b3448bSMatthew Wilcox trace_dax_writeback_one(mapping->host, index, count); 9999973c98eSRoss Zwisler return ret; 10009973c98eSRoss Zwisler 1001a6abc2c0SJan Kara put_unlocked: 10024c3d043dSVivek Goyal put_unlocked_entry(xas, entry, WAKE_NEXT); 10039973c98eSRoss Zwisler return ret; 10049973c98eSRoss Zwisler } 10059973c98eSRoss Zwisler 10069973c98eSRoss Zwisler /* 10079973c98eSRoss Zwisler * Flush the mapping to the persistent domain within the byte range of [start, 10089973c98eSRoss Zwisler * end]. This is required by data integrity operations to ensure file data is 10099973c98eSRoss Zwisler * on persistent storage prior to completion of the operation. 10109973c98eSRoss Zwisler */ 10117f6d5b52SRoss Zwisler int dax_writeback_mapping_range(struct address_space *mapping, 10123f666c56SVivek Goyal struct dax_device *dax_dev, struct writeback_control *wbc) 10139973c98eSRoss Zwisler { 10149fc747f6SMatthew Wilcox XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT); 10159973c98eSRoss Zwisler struct inode *inode = mapping->host; 10169fc747f6SMatthew Wilcox pgoff_t end_index = wbc->range_end >> PAGE_SHIFT; 10179fc747f6SMatthew Wilcox void *entry; 10189fc747f6SMatthew Wilcox int ret = 0; 10199fc747f6SMatthew Wilcox unsigned int scanned = 0; 10209973c98eSRoss Zwisler 10219973c98eSRoss Zwisler if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) 10229973c98eSRoss Zwisler return -EIO; 10239973c98eSRoss Zwisler 10247716506aSMatthew Wilcox (Oracle) if (mapping_empty(mapping) || wbc->sync_mode != WB_SYNC_ALL) 10257f6d5b52SRoss Zwisler return 0; 10267f6d5b52SRoss Zwisler 10279fc747f6SMatthew Wilcox trace_dax_writeback_range(inode, xas.xa_index, end_index); 10289973c98eSRoss Zwisler 10299fc747f6SMatthew Wilcox tag_pages_for_writeback(mapping, xas.xa_index, end_index); 1030d14a3f48SRoss Zwisler 10319fc747f6SMatthew Wilcox xas_lock_irq(&xas); 10329fc747f6SMatthew Wilcox xas_for_each_marked(&xas, entry, end_index, PAGECACHE_TAG_TOWRITE) { 10339fc747f6SMatthew Wilcox ret = dax_writeback_one(&xas, dax_dev, mapping, entry); 1034819ec6b9SJeff Layton if (ret < 0) { 1035819ec6b9SJeff Layton mapping_set_error(mapping, ret); 10369fc747f6SMatthew Wilcox break; 1037d14a3f48SRoss Zwisler } 10389fc747f6SMatthew Wilcox if (++scanned % XA_CHECK_SCHED) 10399fc747f6SMatthew Wilcox continue; 10409fc747f6SMatthew Wilcox 10419fc747f6SMatthew Wilcox xas_pause(&xas); 10429fc747f6SMatthew Wilcox xas_unlock_irq(&xas); 10439fc747f6SMatthew Wilcox cond_resched(); 10449fc747f6SMatthew Wilcox xas_lock_irq(&xas); 1045d14a3f48SRoss Zwisler } 10469fc747f6SMatthew Wilcox xas_unlock_irq(&xas); 10479fc747f6SMatthew Wilcox trace_dax_writeback_range_done(inode, xas.xa_index, end_index); 10489fc747f6SMatthew Wilcox return ret; 10499973c98eSRoss Zwisler } 10509973c98eSRoss Zwisler EXPORT_SYMBOL_GPL(dax_writeback_mapping_range); 10519973c98eSRoss Zwisler 1052e28cd3e5SShiyang Ruan static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos, 1053e28cd3e5SShiyang Ruan size_t size, void **kaddr, pfn_t *pfnp) 10545e161e40SJan Kara { 105560696eb2SChristoph Hellwig pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); 1056e28cd3e5SShiyang Ruan int id, rc = 0; 10575e161e40SJan Kara long length; 10585e161e40SJan Kara 1059cccbce67SDan Williams id = dax_read_lock(); 10605e161e40SJan Kara length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), 1061e28cd3e5SShiyang Ruan DAX_ACCESS, kaddr, pfnp); 10625e161e40SJan Kara if (length < 0) { 10635e161e40SJan Kara rc = length; 10645e161e40SJan Kara goto out; 10655e161e40SJan Kara } 1066e28cd3e5SShiyang Ruan if (!pfnp) 1067e28cd3e5SShiyang Ruan goto out_check_addr; 10685e161e40SJan Kara rc = -EINVAL; 10695e161e40SJan Kara if (PFN_PHYS(length) < size) 10705e161e40SJan Kara goto out; 10715e161e40SJan Kara if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1)) 10725e161e40SJan Kara goto out; 10735e161e40SJan Kara /* For larger pages we need devmap */ 10745e161e40SJan Kara if (length > 1 && !pfn_t_devmap(*pfnp)) 10755e161e40SJan Kara goto out; 10765e161e40SJan Kara rc = 0; 1077e28cd3e5SShiyang Ruan 1078e28cd3e5SShiyang Ruan out_check_addr: 1079e28cd3e5SShiyang Ruan if (!kaddr) 1080e28cd3e5SShiyang Ruan goto out; 1081e28cd3e5SShiyang Ruan if (!*kaddr) 1082e28cd3e5SShiyang Ruan rc = -EFAULT; 10835e161e40SJan Kara out: 1084cccbce67SDan Williams dax_read_unlock(id); 1085cccbce67SDan Williams return rc; 1086cccbce67SDan Williams } 1087f7ca90b1SMatthew Wilcox 1088ff17b8dfSShiyang Ruan /** 1089ff17b8dfSShiyang Ruan * dax_iomap_cow_copy - Copy the data from source to destination before write 1090ff17b8dfSShiyang Ruan * @pos: address to do copy from. 1091ff17b8dfSShiyang Ruan * @length: size of copy operation. 1092ff17b8dfSShiyang Ruan * @align_size: aligned w.r.t align_size (either PMD_SIZE or PAGE_SIZE) 1093ff17b8dfSShiyang Ruan * @srcmap: iomap srcmap 1094ff17b8dfSShiyang Ruan * @daddr: destination address to copy to. 1095ff17b8dfSShiyang Ruan * 1096ff17b8dfSShiyang Ruan * This can be called from two places. Either during DAX write fault (page 1097ff17b8dfSShiyang Ruan * aligned), to copy the length size data to daddr. Or, while doing normal DAX 1098ff17b8dfSShiyang Ruan * write operation, dax_iomap_actor() might call this to do the copy of either 1099ff17b8dfSShiyang Ruan * start or end unaligned address. In the latter case the rest of the copy of 1100ff17b8dfSShiyang Ruan * aligned ranges is taken care by dax_iomap_actor() itself. 1101ff17b8dfSShiyang Ruan */ 1102ff17b8dfSShiyang Ruan static int dax_iomap_cow_copy(loff_t pos, uint64_t length, size_t align_size, 1103ff17b8dfSShiyang Ruan const struct iomap *srcmap, void *daddr) 1104ff17b8dfSShiyang Ruan { 1105ff17b8dfSShiyang Ruan loff_t head_off = pos & (align_size - 1); 1106ff17b8dfSShiyang Ruan size_t size = ALIGN(head_off + length, align_size); 1107ff17b8dfSShiyang Ruan loff_t end = pos + length; 1108ff17b8dfSShiyang Ruan loff_t pg_end = round_up(end, align_size); 1109ff17b8dfSShiyang Ruan bool copy_all = head_off == 0 && end == pg_end; 1110ff17b8dfSShiyang Ruan void *saddr = 0; 1111ff17b8dfSShiyang Ruan int ret = 0; 1112ff17b8dfSShiyang Ruan 1113ff17b8dfSShiyang Ruan ret = dax_iomap_direct_access(srcmap, pos, size, &saddr, NULL); 1114ff17b8dfSShiyang Ruan if (ret) 1115ff17b8dfSShiyang Ruan return ret; 1116ff17b8dfSShiyang Ruan 1117ff17b8dfSShiyang Ruan if (copy_all) { 1118ff17b8dfSShiyang Ruan ret = copy_mc_to_kernel(daddr, saddr, length); 1119ff17b8dfSShiyang Ruan return ret ? -EIO : 0; 1120ff17b8dfSShiyang Ruan } 1121ff17b8dfSShiyang Ruan 1122ff17b8dfSShiyang Ruan /* Copy the head part of the range */ 1123ff17b8dfSShiyang Ruan if (head_off) { 1124ff17b8dfSShiyang Ruan ret = copy_mc_to_kernel(daddr, saddr, head_off); 1125ff17b8dfSShiyang Ruan if (ret) 1126ff17b8dfSShiyang Ruan return -EIO; 1127ff17b8dfSShiyang Ruan } 1128ff17b8dfSShiyang Ruan 1129ff17b8dfSShiyang Ruan /* Copy the tail part of the range */ 1130ff17b8dfSShiyang Ruan if (end < pg_end) { 1131ff17b8dfSShiyang Ruan loff_t tail_off = head_off + length; 1132ff17b8dfSShiyang Ruan loff_t tail_len = pg_end - end; 1133ff17b8dfSShiyang Ruan 1134ff17b8dfSShiyang Ruan ret = copy_mc_to_kernel(daddr + tail_off, saddr + tail_off, 1135ff17b8dfSShiyang Ruan tail_len); 1136ff17b8dfSShiyang Ruan if (ret) 1137ff17b8dfSShiyang Ruan return -EIO; 1138ff17b8dfSShiyang Ruan } 1139ff17b8dfSShiyang Ruan return 0; 1140ff17b8dfSShiyang Ruan } 1141ff17b8dfSShiyang Ruan 11422f89dc12SJan Kara /* 114391d25ba8SRoss Zwisler * The user has performed a load from a hole in the file. Allocating a new 114491d25ba8SRoss Zwisler * page in the file would cause excessive storage usage for workloads with 114591d25ba8SRoss Zwisler * sparse files. Instead we insert a read-only mapping of the 4k zero page. 114691d25ba8SRoss Zwisler * If this page is ever written to we will re-fault and change the mapping to 114791d25ba8SRoss Zwisler * point to real DAX storage instead. 11482f89dc12SJan Kara */ 1149*e5d6df73SShiyang Ruan static vm_fault_t dax_load_hole(struct xa_state *xas, struct vm_fault *vmf, 1150*e5d6df73SShiyang Ruan const struct iomap_iter *iter, void **entry) 1151e30331ffSRoss Zwisler { 1152*e5d6df73SShiyang Ruan struct inode *inode = iter->inode; 115391d25ba8SRoss Zwisler unsigned long vaddr = vmf->address; 1154b90ca5ccSMatthew Wilcox pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr)); 1155b90ca5ccSMatthew Wilcox vm_fault_t ret; 1156e30331ffSRoss Zwisler 1157*e5d6df73SShiyang Ruan *entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, DAX_ZERO_PAGE); 11583159f943SMatthew Wilcox 1159ab77dab4SSouptick Joarder ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); 1160e30331ffSRoss Zwisler trace_dax_load_hole(inode, vmf, ret); 1161e30331ffSRoss Zwisler return ret; 1162e30331ffSRoss Zwisler } 1163e30331ffSRoss Zwisler 1164c2436190SShiyang Ruan #ifdef CONFIG_FS_DAX_PMD 1165c2436190SShiyang Ruan static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, 1166*e5d6df73SShiyang Ruan const struct iomap_iter *iter, void **entry) 1167c2436190SShiyang Ruan { 1168c2436190SShiyang Ruan struct address_space *mapping = vmf->vma->vm_file->f_mapping; 1169c2436190SShiyang Ruan unsigned long pmd_addr = vmf->address & PMD_MASK; 1170c2436190SShiyang Ruan struct vm_area_struct *vma = vmf->vma; 1171c2436190SShiyang Ruan struct inode *inode = mapping->host; 1172c2436190SShiyang Ruan pgtable_t pgtable = NULL; 1173c2436190SShiyang Ruan struct page *zero_page; 1174c2436190SShiyang Ruan spinlock_t *ptl; 1175c2436190SShiyang Ruan pmd_t pmd_entry; 1176c2436190SShiyang Ruan pfn_t pfn; 1177c2436190SShiyang Ruan 1178c2436190SShiyang Ruan zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); 1179c2436190SShiyang Ruan 1180c2436190SShiyang Ruan if (unlikely(!zero_page)) 1181c2436190SShiyang Ruan goto fallback; 1182c2436190SShiyang Ruan 1183c2436190SShiyang Ruan pfn = page_to_pfn_t(zero_page); 1184*e5d6df73SShiyang Ruan *entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, 1185*e5d6df73SShiyang Ruan DAX_PMD | DAX_ZERO_PAGE); 1186c2436190SShiyang Ruan 1187c2436190SShiyang Ruan if (arch_needs_pgtable_deposit()) { 1188c2436190SShiyang Ruan pgtable = pte_alloc_one(vma->vm_mm); 1189c2436190SShiyang Ruan if (!pgtable) 1190c2436190SShiyang Ruan return VM_FAULT_OOM; 1191c2436190SShiyang Ruan } 1192c2436190SShiyang Ruan 1193c2436190SShiyang Ruan ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1194c2436190SShiyang Ruan if (!pmd_none(*(vmf->pmd))) { 1195c2436190SShiyang Ruan spin_unlock(ptl); 1196c2436190SShiyang Ruan goto fallback; 1197c2436190SShiyang Ruan } 1198c2436190SShiyang Ruan 1199c2436190SShiyang Ruan if (pgtable) { 1200c2436190SShiyang Ruan pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 1201c2436190SShiyang Ruan mm_inc_nr_ptes(vma->vm_mm); 1202c2436190SShiyang Ruan } 1203c2436190SShiyang Ruan pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); 1204c2436190SShiyang Ruan pmd_entry = pmd_mkhuge(pmd_entry); 1205c2436190SShiyang Ruan set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); 1206c2436190SShiyang Ruan spin_unlock(ptl); 1207c2436190SShiyang Ruan trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry); 1208c2436190SShiyang Ruan return VM_FAULT_NOPAGE; 1209c2436190SShiyang Ruan 1210c2436190SShiyang Ruan fallback: 1211c2436190SShiyang Ruan if (pgtable) 1212c2436190SShiyang Ruan pte_free(vma->vm_mm, pgtable); 1213c2436190SShiyang Ruan trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); 1214c2436190SShiyang Ruan return VM_FAULT_FALLBACK; 1215c2436190SShiyang Ruan } 1216c2436190SShiyang Ruan #else 1217c2436190SShiyang Ruan static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, 1218*e5d6df73SShiyang Ruan const struct iomap_iter *iter, void **entry) 1219c2436190SShiyang Ruan { 1220c2436190SShiyang Ruan return VM_FAULT_FALLBACK; 1221c2436190SShiyang Ruan } 1222c2436190SShiyang Ruan #endif /* CONFIG_FS_DAX_PMD */ 1223c2436190SShiyang Ruan 1224e5c71954SChristoph Hellwig static int dax_memzero(struct dax_device *dax_dev, pgoff_t pgoff, 1225e5c71954SChristoph Hellwig unsigned int offset, size_t size) 1226e5c71954SChristoph Hellwig { 1227e5c71954SChristoph Hellwig void *kaddr; 1228e5c71954SChristoph Hellwig long ret; 1229e5c71954SChristoph Hellwig 1230e511c4a3SJane Chu ret = dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL); 1231e5c71954SChristoph Hellwig if (ret > 0) { 1232e5c71954SChristoph Hellwig memset(kaddr + offset, 0, size); 1233e5c71954SChristoph Hellwig dax_flush(dax_dev, kaddr + offset, size); 1234e5c71954SChristoph Hellwig } 1235e5c71954SChristoph Hellwig return ret; 1236e5c71954SChristoph Hellwig } 1237e5c71954SChristoph Hellwig 1238c6f40468SChristoph Hellwig static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero) 1239679c8bd3SChristoph Hellwig { 1240c6f40468SChristoph Hellwig const struct iomap *iomap = &iter->iomap; 1241c6f40468SChristoph Hellwig const struct iomap *srcmap = iomap_iter_srcmap(iter); 1242c6f40468SChristoph Hellwig loff_t pos = iter->pos; 1243c6f40468SChristoph Hellwig u64 length = iomap_length(iter); 1244c6f40468SChristoph Hellwig s64 written = 0; 1245c6f40468SChristoph Hellwig 1246c6f40468SChristoph Hellwig /* already zeroed? we're done. */ 1247c6f40468SChristoph Hellwig if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) 1248c6f40468SChristoph Hellwig return length; 1249c6f40468SChristoph Hellwig 1250c6f40468SChristoph Hellwig do { 125181ee8e52SMatthew Wilcox (Oracle) unsigned offset = offset_in_page(pos); 125281ee8e52SMatthew Wilcox (Oracle) unsigned size = min_t(u64, PAGE_SIZE - offset, length); 1253c6f40468SChristoph Hellwig pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); 1254c6f40468SChristoph Hellwig long rc; 1255c6f40468SChristoph Hellwig int id; 12560a23f9ffSVivek Goyal 1257cccbce67SDan Williams id = dax_read_lock(); 1258e5c71954SChristoph Hellwig if (IS_ALIGNED(pos, PAGE_SIZE) && size == PAGE_SIZE) 125981ee8e52SMatthew Wilcox (Oracle) rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1); 12600a23f9ffSVivek Goyal else 1261e5c71954SChristoph Hellwig rc = dax_memzero(iomap->dax_dev, pgoff, offset, size); 1262cccbce67SDan Williams dax_read_unlock(id); 12630a23f9ffSVivek Goyal 1264e5c71954SChristoph Hellwig if (rc < 0) 1265e5c71954SChristoph Hellwig return rc; 1266c6f40468SChristoph Hellwig pos += size; 1267c6f40468SChristoph Hellwig length -= size; 1268c6f40468SChristoph Hellwig written += size; 1269c6f40468SChristoph Hellwig if (did_zero) 1270c6f40468SChristoph Hellwig *did_zero = true; 1271c6f40468SChristoph Hellwig } while (length > 0); 1272c6f40468SChristoph Hellwig 1273c6f40468SChristoph Hellwig return written; 1274679c8bd3SChristoph Hellwig } 1275679c8bd3SChristoph Hellwig 1276c6f40468SChristoph Hellwig int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, 1277c6f40468SChristoph Hellwig const struct iomap_ops *ops) 1278c6f40468SChristoph Hellwig { 1279c6f40468SChristoph Hellwig struct iomap_iter iter = { 1280c6f40468SChristoph Hellwig .inode = inode, 1281c6f40468SChristoph Hellwig .pos = pos, 1282c6f40468SChristoph Hellwig .len = len, 1283952da063SChristoph Hellwig .flags = IOMAP_DAX | IOMAP_ZERO, 1284c6f40468SChristoph Hellwig }; 1285c6f40468SChristoph Hellwig int ret; 1286c6f40468SChristoph Hellwig 1287c6f40468SChristoph Hellwig while ((ret = iomap_iter(&iter, ops)) > 0) 1288c6f40468SChristoph Hellwig iter.processed = dax_zero_iter(&iter, did_zero); 1289c6f40468SChristoph Hellwig return ret; 1290c6f40468SChristoph Hellwig } 1291c6f40468SChristoph Hellwig EXPORT_SYMBOL_GPL(dax_zero_range); 1292c6f40468SChristoph Hellwig 1293c6f40468SChristoph Hellwig int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, 1294c6f40468SChristoph Hellwig const struct iomap_ops *ops) 1295c6f40468SChristoph Hellwig { 1296c6f40468SChristoph Hellwig unsigned int blocksize = i_blocksize(inode); 1297c6f40468SChristoph Hellwig unsigned int off = pos & (blocksize - 1); 1298c6f40468SChristoph Hellwig 1299c6f40468SChristoph Hellwig /* Block boundary? Nothing to do */ 1300c6f40468SChristoph Hellwig if (!off) 1301c6f40468SChristoph Hellwig return 0; 1302c6f40468SChristoph Hellwig return dax_zero_range(inode, pos, blocksize - off, did_zero, ops); 1303c6f40468SChristoph Hellwig } 1304c6f40468SChristoph Hellwig EXPORT_SYMBOL_GPL(dax_truncate_page); 1305c6f40468SChristoph Hellwig 1306ca289e0bSChristoph Hellwig static loff_t dax_iomap_iter(const struct iomap_iter *iomi, 1307ca289e0bSChristoph Hellwig struct iov_iter *iter) 1308a254e568SChristoph Hellwig { 1309ca289e0bSChristoph Hellwig const struct iomap *iomap = &iomi->iomap; 1310ff17b8dfSShiyang Ruan const struct iomap *srcmap = &iomi->srcmap; 1311ca289e0bSChristoph Hellwig loff_t length = iomap_length(iomi); 1312ca289e0bSChristoph Hellwig loff_t pos = iomi->pos; 1313cccbce67SDan Williams struct dax_device *dax_dev = iomap->dax_dev; 1314a254e568SChristoph Hellwig loff_t end = pos + length, done = 0; 1315ff17b8dfSShiyang Ruan bool write = iov_iter_rw(iter) == WRITE; 1316a254e568SChristoph Hellwig ssize_t ret = 0; 1317a77d4786SDan Williams size_t xfer; 1318cccbce67SDan Williams int id; 1319a254e568SChristoph Hellwig 1320ff17b8dfSShiyang Ruan if (!write) { 1321ca289e0bSChristoph Hellwig end = min(end, i_size_read(iomi->inode)); 1322a254e568SChristoph Hellwig if (pos >= end) 1323a254e568SChristoph Hellwig return 0; 1324a254e568SChristoph Hellwig 1325a254e568SChristoph Hellwig if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) 1326a254e568SChristoph Hellwig return iov_iter_zero(min(length, end - pos), iter); 1327a254e568SChristoph Hellwig } 1328a254e568SChristoph Hellwig 1329ff17b8dfSShiyang Ruan /* 1330ff17b8dfSShiyang Ruan * In DAX mode, enforce either pure overwrites of written extents, or 1331ff17b8dfSShiyang Ruan * writes to unwritten extents as part of a copy-on-write operation. 1332ff17b8dfSShiyang Ruan */ 1333ff17b8dfSShiyang Ruan if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED && 1334ff17b8dfSShiyang Ruan !(iomap->flags & IOMAP_F_SHARED))) 1335a254e568SChristoph Hellwig return -EIO; 1336a254e568SChristoph Hellwig 1337e3fce68cSJan Kara /* 1338e3fce68cSJan Kara * Write can allocate block for an area which has a hole page mapped 1339e3fce68cSJan Kara * into page tables. We have to tear down these mappings so that data 1340e3fce68cSJan Kara * written by write(2) is visible in mmap. 1341e3fce68cSJan Kara */ 1342cd656375SJan Kara if (iomap->flags & IOMAP_F_NEW) { 1343ca289e0bSChristoph Hellwig invalidate_inode_pages2_range(iomi->inode->i_mapping, 1344e3fce68cSJan Kara pos >> PAGE_SHIFT, 1345e3fce68cSJan Kara (end - 1) >> PAGE_SHIFT); 1346e3fce68cSJan Kara } 1347e3fce68cSJan Kara 1348cccbce67SDan Williams id = dax_read_lock(); 1349a254e568SChristoph Hellwig while (pos < end) { 1350a254e568SChristoph Hellwig unsigned offset = pos & (PAGE_SIZE - 1); 1351cccbce67SDan Williams const size_t size = ALIGN(length + offset, PAGE_SIZE); 135260696eb2SChristoph Hellwig pgoff_t pgoff = dax_iomap_pgoff(iomap, pos); 1353a254e568SChristoph Hellwig ssize_t map_len; 1354047218ecSJane Chu bool recovery = false; 1355cccbce67SDan Williams void *kaddr; 1356a254e568SChristoph Hellwig 1357d1908f52SMichal Hocko if (fatal_signal_pending(current)) { 1358d1908f52SMichal Hocko ret = -EINTR; 1359d1908f52SMichal Hocko break; 1360d1908f52SMichal Hocko } 1361d1908f52SMichal Hocko 1362cccbce67SDan Williams map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), 1363e511c4a3SJane Chu DAX_ACCESS, &kaddr, NULL); 1364047218ecSJane Chu if (map_len == -EIO && iov_iter_rw(iter) == WRITE) { 1365047218ecSJane Chu map_len = dax_direct_access(dax_dev, pgoff, 1366047218ecSJane Chu PHYS_PFN(size), DAX_RECOVERY_WRITE, 136786ed913bSHuaisheng Ye &kaddr, NULL); 1368047218ecSJane Chu if (map_len > 0) 1369047218ecSJane Chu recovery = true; 1370047218ecSJane Chu } 1371a254e568SChristoph Hellwig if (map_len < 0) { 1372a254e568SChristoph Hellwig ret = map_len; 1373a254e568SChristoph Hellwig break; 1374a254e568SChristoph Hellwig } 1375a254e568SChristoph Hellwig 1376ff17b8dfSShiyang Ruan if (write && 1377ff17b8dfSShiyang Ruan srcmap->type != IOMAP_HOLE && srcmap->addr != iomap->addr) { 1378ff17b8dfSShiyang Ruan ret = dax_iomap_cow_copy(pos, length, PAGE_SIZE, srcmap, 1379ff17b8dfSShiyang Ruan kaddr); 1380ff17b8dfSShiyang Ruan if (ret) 1381ff17b8dfSShiyang Ruan break; 1382ff17b8dfSShiyang Ruan } 1383ff17b8dfSShiyang Ruan 1384cccbce67SDan Williams map_len = PFN_PHYS(map_len); 1385cccbce67SDan Williams kaddr += offset; 1386a254e568SChristoph Hellwig map_len -= offset; 1387a254e568SChristoph Hellwig if (map_len > end - pos) 1388a254e568SChristoph Hellwig map_len = end - pos; 1389a254e568SChristoph Hellwig 1390047218ecSJane Chu if (recovery) 1391047218ecSJane Chu xfer = dax_recovery_write(dax_dev, pgoff, kaddr, 1392047218ecSJane Chu map_len, iter); 1393ff17b8dfSShiyang Ruan else if (write) 1394a77d4786SDan Williams xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, 1395fec53774SDan Williams map_len, iter); 1396a254e568SChristoph Hellwig else 1397a77d4786SDan Williams xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr, 1398b3a9a0c3SDan Williams map_len, iter); 1399a254e568SChristoph Hellwig 1400a77d4786SDan Williams pos += xfer; 1401a77d4786SDan Williams length -= xfer; 1402a77d4786SDan Williams done += xfer; 1403a77d4786SDan Williams 1404a77d4786SDan Williams if (xfer == 0) 1405a77d4786SDan Williams ret = -EFAULT; 1406a77d4786SDan Williams if (xfer < map_len) 1407a77d4786SDan Williams break; 1408a254e568SChristoph Hellwig } 1409cccbce67SDan Williams dax_read_unlock(id); 1410a254e568SChristoph Hellwig 1411a254e568SChristoph Hellwig return done ? done : ret; 1412a254e568SChristoph Hellwig } 1413a254e568SChristoph Hellwig 1414a254e568SChristoph Hellwig /** 141511c59c92SRoss Zwisler * dax_iomap_rw - Perform I/O to a DAX file 1416a254e568SChristoph Hellwig * @iocb: The control block for this I/O 1417a254e568SChristoph Hellwig * @iter: The addresses to do I/O from or to 1418a254e568SChristoph Hellwig * @ops: iomap ops passed from the file system 1419a254e568SChristoph Hellwig * 1420a254e568SChristoph Hellwig * This function performs read and write operations to directly mapped 1421a254e568SChristoph Hellwig * persistent memory. The callers needs to take care of read/write exclusion 1422a254e568SChristoph Hellwig * and evicting any page cache pages in the region under I/O. 1423a254e568SChristoph Hellwig */ 1424a254e568SChristoph Hellwig ssize_t 142511c59c92SRoss Zwisler dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, 14268ff6daa1SChristoph Hellwig const struct iomap_ops *ops) 1427a254e568SChristoph Hellwig { 1428ca289e0bSChristoph Hellwig struct iomap_iter iomi = { 1429ca289e0bSChristoph Hellwig .inode = iocb->ki_filp->f_mapping->host, 1430ca289e0bSChristoph Hellwig .pos = iocb->ki_pos, 1431ca289e0bSChristoph Hellwig .len = iov_iter_count(iter), 1432952da063SChristoph Hellwig .flags = IOMAP_DAX, 1433ca289e0bSChristoph Hellwig }; 1434ca289e0bSChristoph Hellwig loff_t done = 0; 1435ca289e0bSChristoph Hellwig int ret; 1436a254e568SChristoph Hellwig 1437168316dbSChristoph Hellwig if (iov_iter_rw(iter) == WRITE) { 1438ca289e0bSChristoph Hellwig lockdep_assert_held_write(&iomi.inode->i_rwsem); 1439ca289e0bSChristoph Hellwig iomi.flags |= IOMAP_WRITE; 1440168316dbSChristoph Hellwig } else { 1441ca289e0bSChristoph Hellwig lockdep_assert_held(&iomi.inode->i_rwsem); 1442168316dbSChristoph Hellwig } 1443a254e568SChristoph Hellwig 144496222d53SJeff Moyer if (iocb->ki_flags & IOCB_NOWAIT) 1445ca289e0bSChristoph Hellwig iomi.flags |= IOMAP_NOWAIT; 144696222d53SJeff Moyer 1447ca289e0bSChristoph Hellwig while ((ret = iomap_iter(&iomi, ops)) > 0) 1448ca289e0bSChristoph Hellwig iomi.processed = dax_iomap_iter(&iomi, iter); 1449a254e568SChristoph Hellwig 1450ca289e0bSChristoph Hellwig done = iomi.pos - iocb->ki_pos; 1451ca289e0bSChristoph Hellwig iocb->ki_pos = iomi.pos; 1452a254e568SChristoph Hellwig return done ? done : ret; 1453a254e568SChristoph Hellwig } 145411c59c92SRoss Zwisler EXPORT_SYMBOL_GPL(dax_iomap_rw); 1455a7d73fe6SChristoph Hellwig 1456ab77dab4SSouptick Joarder static vm_fault_t dax_fault_return(int error) 14579f141d6eSJan Kara { 14589f141d6eSJan Kara if (error == 0) 14599f141d6eSJan Kara return VM_FAULT_NOPAGE; 1460c9aed74eSSouptick Joarder return vmf_error(error); 14619f141d6eSJan Kara } 14629f141d6eSJan Kara 1463aaa422c4SDan Williams /* 146455f81639SShiyang Ruan * When handling a synchronous page fault and the inode need a fsync, we can 146555f81639SShiyang Ruan * insert the PTE/PMD into page tables only after that fsync happened. Skip 146655f81639SShiyang Ruan * insertion for now and return the pfn so that caller can insert it after the 146755f81639SShiyang Ruan * fsync is done. 146855f81639SShiyang Ruan */ 146955f81639SShiyang Ruan static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn) 147055f81639SShiyang Ruan { 147155f81639SShiyang Ruan if (WARN_ON_ONCE(!pfnp)) 147255f81639SShiyang Ruan return VM_FAULT_SIGBUS; 147355f81639SShiyang Ruan *pfnp = pfn; 147455f81639SShiyang Ruan return VM_FAULT_NEEDDSYNC; 147555f81639SShiyang Ruan } 147655f81639SShiyang Ruan 147765dd814aSChristoph Hellwig static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf, 147865dd814aSChristoph Hellwig const struct iomap_iter *iter) 147955f81639SShiyang Ruan { 148055f81639SShiyang Ruan vm_fault_t ret; 148155f81639SShiyang Ruan int error = 0; 148255f81639SShiyang Ruan 148365dd814aSChristoph Hellwig switch (iter->iomap.type) { 148455f81639SShiyang Ruan case IOMAP_HOLE: 148555f81639SShiyang Ruan case IOMAP_UNWRITTEN: 1486429f8de7SChristoph Hellwig clear_user_highpage(vmf->cow_page, vmf->address); 148755f81639SShiyang Ruan break; 148855f81639SShiyang Ruan case IOMAP_MAPPED: 1489429f8de7SChristoph Hellwig error = copy_cow_page_dax(vmf, iter); 149055f81639SShiyang Ruan break; 149155f81639SShiyang Ruan default: 149255f81639SShiyang Ruan WARN_ON_ONCE(1); 149355f81639SShiyang Ruan error = -EIO; 149455f81639SShiyang Ruan break; 149555f81639SShiyang Ruan } 149655f81639SShiyang Ruan 149755f81639SShiyang Ruan if (error) 149855f81639SShiyang Ruan return dax_fault_return(error); 149955f81639SShiyang Ruan 150055f81639SShiyang Ruan __SetPageUptodate(vmf->cow_page); 150155f81639SShiyang Ruan ret = finish_fault(vmf); 150255f81639SShiyang Ruan if (!ret) 150355f81639SShiyang Ruan return VM_FAULT_DONE_COW; 150455f81639SShiyang Ruan return ret; 150555f81639SShiyang Ruan } 150655f81639SShiyang Ruan 1507c2436190SShiyang Ruan /** 150865dd814aSChristoph Hellwig * dax_fault_iter - Common actor to handle pfn insertion in PTE/PMD fault. 1509c2436190SShiyang Ruan * @vmf: vm fault instance 151065dd814aSChristoph Hellwig * @iter: iomap iter 1511c2436190SShiyang Ruan * @pfnp: pfn to be returned 1512c2436190SShiyang Ruan * @xas: the dax mapping tree of a file 1513c2436190SShiyang Ruan * @entry: an unlocked dax entry to be inserted 1514c2436190SShiyang Ruan * @pmd: distinguish whether it is a pmd fault 1515c2436190SShiyang Ruan */ 151665dd814aSChristoph Hellwig static vm_fault_t dax_fault_iter(struct vm_fault *vmf, 151765dd814aSChristoph Hellwig const struct iomap_iter *iter, pfn_t *pfnp, 151865dd814aSChristoph Hellwig struct xa_state *xas, void **entry, bool pmd) 1519c2436190SShiyang Ruan { 152065dd814aSChristoph Hellwig const struct iomap *iomap = &iter->iomap; 1521ff17b8dfSShiyang Ruan const struct iomap *srcmap = &iter->srcmap; 1522c2436190SShiyang Ruan size_t size = pmd ? PMD_SIZE : PAGE_SIZE; 1523c2436190SShiyang Ruan loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT; 1524*e5d6df73SShiyang Ruan bool write = iter->flags & IOMAP_WRITE; 1525c2436190SShiyang Ruan unsigned long entry_flags = pmd ? DAX_PMD : 0; 1526c2436190SShiyang Ruan int err = 0; 1527c2436190SShiyang Ruan pfn_t pfn; 1528ff17b8dfSShiyang Ruan void *kaddr; 1529c2436190SShiyang Ruan 153065dd814aSChristoph Hellwig if (!pmd && vmf->cow_page) 153165dd814aSChristoph Hellwig return dax_fault_cow_page(vmf, iter); 153265dd814aSChristoph Hellwig 1533c2436190SShiyang Ruan /* if we are reading UNWRITTEN and HOLE, return a hole. */ 1534c2436190SShiyang Ruan if (!write && 1535c2436190SShiyang Ruan (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { 1536c2436190SShiyang Ruan if (!pmd) 1537*e5d6df73SShiyang Ruan return dax_load_hole(xas, vmf, iter, entry); 1538*e5d6df73SShiyang Ruan return dax_pmd_load_hole(xas, vmf, iter, entry); 1539c2436190SShiyang Ruan } 1540c2436190SShiyang Ruan 1541ff17b8dfSShiyang Ruan if (iomap->type != IOMAP_MAPPED && !(iomap->flags & IOMAP_F_SHARED)) { 1542c2436190SShiyang Ruan WARN_ON_ONCE(1); 1543c2436190SShiyang Ruan return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS; 1544c2436190SShiyang Ruan } 1545c2436190SShiyang Ruan 1546ff17b8dfSShiyang Ruan err = dax_iomap_direct_access(iomap, pos, size, &kaddr, &pfn); 1547c2436190SShiyang Ruan if (err) 1548c2436190SShiyang Ruan return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err); 1549c2436190SShiyang Ruan 1550*e5d6df73SShiyang Ruan *entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, entry_flags); 1551c2436190SShiyang Ruan 1552ff17b8dfSShiyang Ruan if (write && 1553ff17b8dfSShiyang Ruan srcmap->type != IOMAP_HOLE && srcmap->addr != iomap->addr) { 1554ff17b8dfSShiyang Ruan err = dax_iomap_cow_copy(pos, size, size, srcmap, kaddr); 1555ff17b8dfSShiyang Ruan if (err) 1556ff17b8dfSShiyang Ruan return dax_fault_return(err); 1557ff17b8dfSShiyang Ruan } 1558ff17b8dfSShiyang Ruan 1559*e5d6df73SShiyang Ruan if (dax_fault_is_synchronous(iter, vmf->vma)) 1560c2436190SShiyang Ruan return dax_fault_synchronous_pfnp(pfnp, pfn); 1561c2436190SShiyang Ruan 1562c2436190SShiyang Ruan /* insert PMD pfn */ 1563c2436190SShiyang Ruan if (pmd) 1564c2436190SShiyang Ruan return vmf_insert_pfn_pmd(vmf, pfn, write); 1565c2436190SShiyang Ruan 1566c2436190SShiyang Ruan /* insert PTE pfn */ 1567c2436190SShiyang Ruan if (write) 1568c2436190SShiyang Ruan return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); 1569c2436190SShiyang Ruan return vmf_insert_mixed(vmf->vma, vmf->address, pfn); 1570c2436190SShiyang Ruan } 1571c2436190SShiyang Ruan 1572ab77dab4SSouptick Joarder static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, 1573c0b24625SJan Kara int *iomap_errp, const struct iomap_ops *ops) 1574a7d73fe6SChristoph Hellwig { 157565dd814aSChristoph Hellwig struct address_space *mapping = vmf->vma->vm_file->f_mapping; 1576b15cd800SMatthew Wilcox XA_STATE(xas, &mapping->i_pages, vmf->pgoff); 157765dd814aSChristoph Hellwig struct iomap_iter iter = { 157865dd814aSChristoph Hellwig .inode = mapping->host, 157965dd814aSChristoph Hellwig .pos = (loff_t)vmf->pgoff << PAGE_SHIFT, 158065dd814aSChristoph Hellwig .len = PAGE_SIZE, 1581952da063SChristoph Hellwig .flags = IOMAP_DAX | IOMAP_FAULT, 158265dd814aSChristoph Hellwig }; 1583ab77dab4SSouptick Joarder vm_fault_t ret = 0; 1584a7d73fe6SChristoph Hellwig void *entry; 158565dd814aSChristoph Hellwig int error; 1586a7d73fe6SChristoph Hellwig 158765dd814aSChristoph Hellwig trace_dax_pte_fault(iter.inode, vmf, ret); 1588a7d73fe6SChristoph Hellwig /* 1589a7d73fe6SChristoph Hellwig * Check whether offset isn't beyond end of file now. Caller is supposed 1590a7d73fe6SChristoph Hellwig * to hold locks serializing us with truncate / punch hole so this is 1591a7d73fe6SChristoph Hellwig * a reliable test. 1592a7d73fe6SChristoph Hellwig */ 159365dd814aSChristoph Hellwig if (iter.pos >= i_size_read(iter.inode)) { 1594ab77dab4SSouptick Joarder ret = VM_FAULT_SIGBUS; 1595a9c42b33SRoss Zwisler goto out; 1596a9c42b33SRoss Zwisler } 1597a7d73fe6SChristoph Hellwig 159865dd814aSChristoph Hellwig if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page) 159965dd814aSChristoph Hellwig iter.flags |= IOMAP_WRITE; 1600a7d73fe6SChristoph Hellwig 1601b15cd800SMatthew Wilcox entry = grab_mapping_entry(&xas, mapping, 0); 1602b15cd800SMatthew Wilcox if (xa_is_internal(entry)) { 1603b15cd800SMatthew Wilcox ret = xa_to_internal(entry); 160413e451fdSJan Kara goto out; 160513e451fdSJan Kara } 160613e451fdSJan Kara 1607a7d73fe6SChristoph Hellwig /* 1608e2093926SRoss Zwisler * It is possible, particularly with mixed reads & writes to private 1609e2093926SRoss Zwisler * mappings, that we have raced with a PMD fault that overlaps with 1610e2093926SRoss Zwisler * the PTE we need to set up. If so just return and the fault will be 1611e2093926SRoss Zwisler * retried. 1612e2093926SRoss Zwisler */ 1613e2093926SRoss Zwisler if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) { 1614ab77dab4SSouptick Joarder ret = VM_FAULT_NOPAGE; 1615e2093926SRoss Zwisler goto unlock_entry; 1616e2093926SRoss Zwisler } 1617e2093926SRoss Zwisler 161865dd814aSChristoph Hellwig while ((error = iomap_iter(&iter, ops)) > 0) { 161965dd814aSChristoph Hellwig if (WARN_ON_ONCE(iomap_length(&iter) < PAGE_SIZE)) { 162065dd814aSChristoph Hellwig iter.processed = -EIO; /* fs corruption? */ 162165dd814aSChristoph Hellwig continue; 162265dd814aSChristoph Hellwig } 162365dd814aSChristoph Hellwig 162465dd814aSChristoph Hellwig ret = dax_fault_iter(vmf, &iter, pfnp, &xas, &entry, false); 162565dd814aSChristoph Hellwig if (ret != VM_FAULT_SIGBUS && 162665dd814aSChristoph Hellwig (iter.iomap.flags & IOMAP_F_NEW)) { 162765dd814aSChristoph Hellwig count_vm_event(PGMAJFAULT); 162865dd814aSChristoph Hellwig count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); 162965dd814aSChristoph Hellwig ret |= VM_FAULT_MAJOR; 163065dd814aSChristoph Hellwig } 163165dd814aSChristoph Hellwig 163265dd814aSChristoph Hellwig if (!(ret & VM_FAULT_ERROR)) 163365dd814aSChristoph Hellwig iter.processed = PAGE_SIZE; 163465dd814aSChristoph Hellwig } 163565dd814aSChristoph Hellwig 1636c0b24625SJan Kara if (iomap_errp) 1637c0b24625SJan Kara *iomap_errp = error; 163865dd814aSChristoph Hellwig if (!ret && error) 1639ab77dab4SSouptick Joarder ret = dax_fault_return(error); 1640a7d73fe6SChristoph Hellwig 164113e451fdSJan Kara unlock_entry: 1642b15cd800SMatthew Wilcox dax_unlock_entry(&xas, entry); 1643a9c42b33SRoss Zwisler out: 164465dd814aSChristoph Hellwig trace_dax_pte_fault_done(iter.inode, vmf, ret); 164565dd814aSChristoph Hellwig return ret; 1646a7d73fe6SChristoph Hellwig } 1647642261acSRoss Zwisler 1648642261acSRoss Zwisler #ifdef CONFIG_FS_DAX_PMD 164955f81639SShiyang Ruan static bool dax_fault_check_fallback(struct vm_fault *vmf, struct xa_state *xas, 165055f81639SShiyang Ruan pgoff_t max_pgoff) 1651642261acSRoss Zwisler { 1652d8a849e1SDave Jiang unsigned long pmd_addr = vmf->address & PMD_MASK; 1653d8a849e1SDave Jiang bool write = vmf->flags & FAULT_FLAG_WRITE; 1654282a8e03SRoss Zwisler 1655fffa281bSRoss Zwisler /* 1656fffa281bSRoss Zwisler * Make sure that the faulting address's PMD offset (color) matches 1657fffa281bSRoss Zwisler * the PMD offset from the start of the file. This is necessary so 1658fffa281bSRoss Zwisler * that a PMD range in the page table overlaps exactly with a PMD 1659a77d19f4SMatthew Wilcox * range in the page cache. 1660fffa281bSRoss Zwisler */ 1661fffa281bSRoss Zwisler if ((vmf->pgoff & PG_PMD_COLOUR) != 1662fffa281bSRoss Zwisler ((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR)) 166355f81639SShiyang Ruan return true; 1664fffa281bSRoss Zwisler 1665642261acSRoss Zwisler /* Fall back to PTEs if we're going to COW */ 166655f81639SShiyang Ruan if (write && !(vmf->vma->vm_flags & VM_SHARED)) 166755f81639SShiyang Ruan return true; 1668642261acSRoss Zwisler 1669642261acSRoss Zwisler /* If the PMD would extend outside the VMA */ 167055f81639SShiyang Ruan if (pmd_addr < vmf->vma->vm_start) 167155f81639SShiyang Ruan return true; 167255f81639SShiyang Ruan if ((pmd_addr + PMD_SIZE) > vmf->vma->vm_end) 167355f81639SShiyang Ruan return true; 167455f81639SShiyang Ruan 167555f81639SShiyang Ruan /* If the PMD would extend beyond the file size */ 167655f81639SShiyang Ruan if ((xas->xa_index | PG_PMD_COLOUR) >= max_pgoff) 167755f81639SShiyang Ruan return true; 167855f81639SShiyang Ruan 167955f81639SShiyang Ruan return false; 168055f81639SShiyang Ruan } 168155f81639SShiyang Ruan 1682642261acSRoss Zwisler static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, 1683642261acSRoss Zwisler const struct iomap_ops *ops) 1684642261acSRoss Zwisler { 168565dd814aSChristoph Hellwig struct address_space *mapping = vmf->vma->vm_file->f_mapping; 1686642261acSRoss Zwisler XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER); 168765dd814aSChristoph Hellwig struct iomap_iter iter = { 168865dd814aSChristoph Hellwig .inode = mapping->host, 168965dd814aSChristoph Hellwig .len = PMD_SIZE, 1690952da063SChristoph Hellwig .flags = IOMAP_DAX | IOMAP_FAULT, 169165dd814aSChristoph Hellwig }; 1692c2436190SShiyang Ruan vm_fault_t ret = VM_FAULT_FALLBACK; 1693642261acSRoss Zwisler pgoff_t max_pgoff; 1694642261acSRoss Zwisler void *entry; 1695642261acSRoss Zwisler int error; 1696642261acSRoss Zwisler 169765dd814aSChristoph Hellwig if (vmf->flags & FAULT_FLAG_WRITE) 169865dd814aSChristoph Hellwig iter.flags |= IOMAP_WRITE; 169965dd814aSChristoph Hellwig 1700642261acSRoss Zwisler /* 1701642261acSRoss Zwisler * Check whether offset isn't beyond end of file now. Caller is 1702642261acSRoss Zwisler * supposed to hold locks serializing us with truncate / punch hole so 1703642261acSRoss Zwisler * this is a reliable test. 1704642261acSRoss Zwisler */ 170565dd814aSChristoph Hellwig max_pgoff = DIV_ROUND_UP(i_size_read(iter.inode), PAGE_SIZE); 1706642261acSRoss Zwisler 170765dd814aSChristoph Hellwig trace_dax_pmd_fault(iter.inode, vmf, max_pgoff, 0); 1708642261acSRoss Zwisler 1709b15cd800SMatthew Wilcox if (xas.xa_index >= max_pgoff) { 1710c2436190SShiyang Ruan ret = VM_FAULT_SIGBUS; 1711282a8e03SRoss Zwisler goto out; 1712282a8e03SRoss Zwisler } 1713642261acSRoss Zwisler 171455f81639SShiyang Ruan if (dax_fault_check_fallback(vmf, &xas, max_pgoff)) 1715642261acSRoss Zwisler goto fallback; 1716642261acSRoss Zwisler 1717642261acSRoss Zwisler /* 1718b15cd800SMatthew Wilcox * grab_mapping_entry() will make sure we get an empty PMD entry, 1719b15cd800SMatthew Wilcox * a zero PMD entry or a DAX PMD. If it can't (because a PTE 1720b15cd800SMatthew Wilcox * entry is already in the array, for instance), it will return 1721b15cd800SMatthew Wilcox * VM_FAULT_FALLBACK. 17229f141d6eSJan Kara */ 172323c84eb7SMatthew Wilcox (Oracle) entry = grab_mapping_entry(&xas, mapping, PMD_ORDER); 1724b15cd800SMatthew Wilcox if (xa_is_internal(entry)) { 1725c2436190SShiyang Ruan ret = xa_to_internal(entry); 1726876f2946SRoss Zwisler goto fallback; 1727b15cd800SMatthew Wilcox } 1728876f2946SRoss Zwisler 1729876f2946SRoss Zwisler /* 1730e2093926SRoss Zwisler * It is possible, particularly with mixed reads & writes to private 1731e2093926SRoss Zwisler * mappings, that we have raced with a PTE fault that overlaps with 1732e2093926SRoss Zwisler * the PMD we need to set up. If so just return and the fault will be 1733e2093926SRoss Zwisler * retried. 1734e2093926SRoss Zwisler */ 1735e2093926SRoss Zwisler if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) && 1736e2093926SRoss Zwisler !pmd_devmap(*vmf->pmd)) { 1737c2436190SShiyang Ruan ret = 0; 1738e2093926SRoss Zwisler goto unlock_entry; 1739e2093926SRoss Zwisler } 1740e2093926SRoss Zwisler 174165dd814aSChristoph Hellwig iter.pos = (loff_t)xas.xa_index << PAGE_SHIFT; 174265dd814aSChristoph Hellwig while ((error = iomap_iter(&iter, ops)) > 0) { 174365dd814aSChristoph Hellwig if (iomap_length(&iter) < PMD_SIZE) 174465dd814aSChristoph Hellwig continue; /* actually breaks out of the loop */ 1745876f2946SRoss Zwisler 174665dd814aSChristoph Hellwig ret = dax_fault_iter(vmf, &iter, pfnp, &xas, &entry, true); 174765dd814aSChristoph Hellwig if (ret != VM_FAULT_FALLBACK) 174865dd814aSChristoph Hellwig iter.processed = PMD_SIZE; 1749caa51d26SJan Kara } 1750caa51d26SJan Kara 1751876f2946SRoss Zwisler unlock_entry: 1752b15cd800SMatthew Wilcox dax_unlock_entry(&xas, entry); 1753642261acSRoss Zwisler fallback: 1754c2436190SShiyang Ruan if (ret == VM_FAULT_FALLBACK) { 175565dd814aSChristoph Hellwig split_huge_pmd(vmf->vma, vmf->pmd, vmf->address); 1756642261acSRoss Zwisler count_vm_event(THP_FAULT_FALLBACK); 1757642261acSRoss Zwisler } 1758282a8e03SRoss Zwisler out: 175965dd814aSChristoph Hellwig trace_dax_pmd_fault_done(iter.inode, vmf, max_pgoff, ret); 1760c2436190SShiyang Ruan return ret; 1761642261acSRoss Zwisler } 1762a2d58167SDave Jiang #else 1763ab77dab4SSouptick Joarder static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, 176401cddfe9SArnd Bergmann const struct iomap_ops *ops) 1765a2d58167SDave Jiang { 1766a2d58167SDave Jiang return VM_FAULT_FALLBACK; 1767a2d58167SDave Jiang } 1768642261acSRoss Zwisler #endif /* CONFIG_FS_DAX_PMD */ 1769a2d58167SDave Jiang 1770a2d58167SDave Jiang /** 1771a2d58167SDave Jiang * dax_iomap_fault - handle a page fault on a DAX file 1772a2d58167SDave Jiang * @vmf: The description of the fault 1773cec04e8cSJan Kara * @pe_size: Size of the page to fault in 17749a0dd422SJan Kara * @pfnp: PFN to insert for synchronous faults if fsync is required 1775c0b24625SJan Kara * @iomap_errp: Storage for detailed error code in case of error 1776cec04e8cSJan Kara * @ops: Iomap ops passed from the file system 1777a2d58167SDave Jiang * 1778a2d58167SDave Jiang * When a page fault occurs, filesystems may call this helper in 1779a2d58167SDave Jiang * their fault handler for DAX files. dax_iomap_fault() assumes the caller 1780a2d58167SDave Jiang * has done all the necessary locking for page fault to proceed 1781a2d58167SDave Jiang * successfully. 1782a2d58167SDave Jiang */ 1783ab77dab4SSouptick Joarder vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size, 1784c0b24625SJan Kara pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops) 1785a2d58167SDave Jiang { 1786c791ace1SDave Jiang switch (pe_size) { 1787c791ace1SDave Jiang case PE_SIZE_PTE: 1788c0b24625SJan Kara return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops); 1789c791ace1SDave Jiang case PE_SIZE_PMD: 17909a0dd422SJan Kara return dax_iomap_pmd_fault(vmf, pfnp, ops); 1791a2d58167SDave Jiang default: 1792a2d58167SDave Jiang return VM_FAULT_FALLBACK; 1793a2d58167SDave Jiang } 1794a2d58167SDave Jiang } 1795a2d58167SDave Jiang EXPORT_SYMBOL_GPL(dax_iomap_fault); 179671eab6dfSJan Kara 1797a77d19f4SMatthew Wilcox /* 179871eab6dfSJan Kara * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables 179971eab6dfSJan Kara * @vmf: The description of the fault 180071eab6dfSJan Kara * @pfn: PFN to insert 1801cfc93c6cSMatthew Wilcox * @order: Order of entry to insert. 180271eab6dfSJan Kara * 1803a77d19f4SMatthew Wilcox * This function inserts a writeable PTE or PMD entry into the page tables 1804a77d19f4SMatthew Wilcox * for an mmaped DAX file. It also marks the page cache entry as dirty. 180571eab6dfSJan Kara */ 1806cfc93c6cSMatthew Wilcox static vm_fault_t 1807cfc93c6cSMatthew Wilcox dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order) 180871eab6dfSJan Kara { 180971eab6dfSJan Kara struct address_space *mapping = vmf->vma->vm_file->f_mapping; 1810cfc93c6cSMatthew Wilcox XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, order); 1811cfc93c6cSMatthew Wilcox void *entry; 1812ab77dab4SSouptick Joarder vm_fault_t ret; 181371eab6dfSJan Kara 1814cfc93c6cSMatthew Wilcox xas_lock_irq(&xas); 181523c84eb7SMatthew Wilcox (Oracle) entry = get_unlocked_entry(&xas, order); 181671eab6dfSJan Kara /* Did we race with someone splitting entry or so? */ 181723c84eb7SMatthew Wilcox (Oracle) if (!entry || dax_is_conflict(entry) || 181823c84eb7SMatthew Wilcox (Oracle) (order == 0 && !dax_is_pte_entry(entry))) { 18194c3d043dSVivek Goyal put_unlocked_entry(&xas, entry, WAKE_NEXT); 1820cfc93c6cSMatthew Wilcox xas_unlock_irq(&xas); 182171eab6dfSJan Kara trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf, 182271eab6dfSJan Kara VM_FAULT_NOPAGE); 182371eab6dfSJan Kara return VM_FAULT_NOPAGE; 182471eab6dfSJan Kara } 1825cfc93c6cSMatthew Wilcox xas_set_mark(&xas, PAGECACHE_TAG_DIRTY); 1826cfc93c6cSMatthew Wilcox dax_lock_entry(&xas, entry); 1827cfc93c6cSMatthew Wilcox xas_unlock_irq(&xas); 1828cfc93c6cSMatthew Wilcox if (order == 0) 1829ab77dab4SSouptick Joarder ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); 183071eab6dfSJan Kara #ifdef CONFIG_FS_DAX_PMD 1831cfc93c6cSMatthew Wilcox else if (order == PMD_ORDER) 1832fce86ff5SDan Williams ret = vmf_insert_pfn_pmd(vmf, pfn, FAULT_FLAG_WRITE); 183371eab6dfSJan Kara #endif 1834cfc93c6cSMatthew Wilcox else 1835ab77dab4SSouptick Joarder ret = VM_FAULT_FALLBACK; 1836cfc93c6cSMatthew Wilcox dax_unlock_entry(&xas, entry); 1837ab77dab4SSouptick Joarder trace_dax_insert_pfn_mkwrite(mapping->host, vmf, ret); 1838ab77dab4SSouptick Joarder return ret; 183971eab6dfSJan Kara } 184071eab6dfSJan Kara 184171eab6dfSJan Kara /** 184271eab6dfSJan Kara * dax_finish_sync_fault - finish synchronous page fault 184371eab6dfSJan Kara * @vmf: The description of the fault 184471eab6dfSJan Kara * @pe_size: Size of entry to be inserted 184571eab6dfSJan Kara * @pfn: PFN to insert 184671eab6dfSJan Kara * 184771eab6dfSJan Kara * This function ensures that the file range touched by the page fault is 184871eab6dfSJan Kara * stored persistently on the media and handles inserting of appropriate page 184971eab6dfSJan Kara * table entry. 185071eab6dfSJan Kara */ 1851ab77dab4SSouptick Joarder vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf, 1852ab77dab4SSouptick Joarder enum page_entry_size pe_size, pfn_t pfn) 185371eab6dfSJan Kara { 185471eab6dfSJan Kara int err; 185571eab6dfSJan Kara loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT; 1856cfc93c6cSMatthew Wilcox unsigned int order = pe_order(pe_size); 1857cfc93c6cSMatthew Wilcox size_t len = PAGE_SIZE << order; 185871eab6dfSJan Kara 185971eab6dfSJan Kara err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1); 186071eab6dfSJan Kara if (err) 186171eab6dfSJan Kara return VM_FAULT_SIGBUS; 1862cfc93c6cSMatthew Wilcox return dax_insert_pfn_mkwrite(vmf, pfn, order); 186371eab6dfSJan Kara } 186471eab6dfSJan Kara EXPORT_SYMBOL_GPL(dax_finish_sync_fault); 1865