11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * fs/fs-writeback.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2002, Linus Torvalds. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Contains all the functions related to writing back and waiting 71da177e4SLinus Torvalds * upon dirty inodes against superblocks, and writing back dirty 81da177e4SLinus Torvalds * pages against inodes. ie: data writeback. Writeout of the 91da177e4SLinus Torvalds * inode itself is not handled here. 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * 10Apr2002 akpm@zip.com.au 121da177e4SLinus Torvalds * Split out of fs/inode.c 131da177e4SLinus Torvalds * Additions for address_space-based writeback 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds 161da177e4SLinus Torvalds #include <linux/kernel.h> 171da177e4SLinus Torvalds #include <linux/spinlock.h> 181da177e4SLinus Torvalds #include <linux/sched.h> 191da177e4SLinus Torvalds #include <linux/fs.h> 201da177e4SLinus Torvalds #include <linux/mm.h> 211da177e4SLinus Torvalds #include <linux/writeback.h> 221da177e4SLinus Torvalds #include <linux/blkdev.h> 231da177e4SLinus Torvalds #include <linux/backing-dev.h> 241da177e4SLinus Torvalds #include <linux/buffer_head.h> 251da177e4SLinus Torvalds 261da177e4SLinus Torvalds extern struct super_block *blockdev_superblock; 271da177e4SLinus Torvalds 281da177e4SLinus Torvalds /** 291da177e4SLinus Torvalds * __mark_inode_dirty - internal function 301da177e4SLinus Torvalds * @inode: inode to mark 311da177e4SLinus Torvalds * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) 321da177e4SLinus Torvalds * Mark an inode as dirty. Callers should use mark_inode_dirty or 331da177e4SLinus Torvalds * mark_inode_dirty_sync. 341da177e4SLinus Torvalds * 351da177e4SLinus Torvalds * Put the inode on the super block's dirty list. 361da177e4SLinus Torvalds * 371da177e4SLinus Torvalds * CAREFUL! We mark it dirty unconditionally, but move it onto the 381da177e4SLinus Torvalds * dirty list only if it is hashed or if it refers to a blockdev. 391da177e4SLinus Torvalds * If it was not hashed, it will never be added to the dirty list 401da177e4SLinus Torvalds * even if it is later hashed, as it will have been marked dirty already. 411da177e4SLinus Torvalds * 421da177e4SLinus Torvalds * In short, make sure you hash any inodes _before_ you start marking 431da177e4SLinus Torvalds * them dirty. 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * This function *must* be atomic for the I_DIRTY_PAGES case - 461da177e4SLinus Torvalds * set_page_dirty() is called under spinlock in several places. 471da177e4SLinus Torvalds * 481da177e4SLinus Torvalds * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 491da177e4SLinus Torvalds * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 501da177e4SLinus Torvalds * the kernel-internal blockdev inode represents the dirtying time of the 511da177e4SLinus Torvalds * blockdev's pages. This is why for I_DIRTY_PAGES we always use 521da177e4SLinus Torvalds * page->mapping->host, so the page-dirtying time is recorded in the internal 531da177e4SLinus Torvalds * blockdev inode. 541da177e4SLinus Torvalds */ 551da177e4SLinus Torvalds void __mark_inode_dirty(struct inode *inode, int flags) 561da177e4SLinus Torvalds { 571da177e4SLinus Torvalds struct super_block *sb = inode->i_sb; 581da177e4SLinus Torvalds 591da177e4SLinus Torvalds /* 601da177e4SLinus Torvalds * Don't do this for I_DIRTY_PAGES - that doesn't actually 611da177e4SLinus Torvalds * dirty the inode itself 621da177e4SLinus Torvalds */ 631da177e4SLinus Torvalds if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 641da177e4SLinus Torvalds if (sb->s_op->dirty_inode) 651da177e4SLinus Torvalds sb->s_op->dirty_inode(inode); 661da177e4SLinus Torvalds } 671da177e4SLinus Torvalds 681da177e4SLinus Torvalds /* 691da177e4SLinus Torvalds * make sure that changes are seen by all cpus before we test i_state 701da177e4SLinus Torvalds * -- mikulas 711da177e4SLinus Torvalds */ 721da177e4SLinus Torvalds smp_mb(); 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* avoid the locking if we can */ 751da177e4SLinus Torvalds if ((inode->i_state & flags) == flags) 761da177e4SLinus Torvalds return; 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds if (unlikely(block_dump)) { 791da177e4SLinus Torvalds struct dentry *dentry = NULL; 801da177e4SLinus Torvalds const char *name = "?"; 811da177e4SLinus Torvalds 821da177e4SLinus Torvalds if (!list_empty(&inode->i_dentry)) { 831da177e4SLinus Torvalds dentry = list_entry(inode->i_dentry.next, 841da177e4SLinus Torvalds struct dentry, d_alias); 851da177e4SLinus Torvalds if (dentry && dentry->d_name.name) 861da177e4SLinus Torvalds name = (const char *) dentry->d_name.name; 871da177e4SLinus Torvalds } 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) 901da177e4SLinus Torvalds printk(KERN_DEBUG 911da177e4SLinus Torvalds "%s(%d): dirtied inode %lu (%s) on %s\n", 921da177e4SLinus Torvalds current->comm, current->pid, inode->i_ino, 931da177e4SLinus Torvalds name, inode->i_sb->s_id); 941da177e4SLinus Torvalds } 951da177e4SLinus Torvalds 961da177e4SLinus Torvalds spin_lock(&inode_lock); 971da177e4SLinus Torvalds if ((inode->i_state & flags) != flags) { 981da177e4SLinus Torvalds const int was_dirty = inode->i_state & I_DIRTY; 991da177e4SLinus Torvalds 1001da177e4SLinus Torvalds inode->i_state |= flags; 1011da177e4SLinus Torvalds 1021da177e4SLinus Torvalds /* 1031da177e4SLinus Torvalds * If the inode is locked, just update its dirty state. 1041da177e4SLinus Torvalds * The unlocker will place the inode on the appropriate 1051da177e4SLinus Torvalds * superblock list, based upon its state. 1061da177e4SLinus Torvalds */ 1071da177e4SLinus Torvalds if (inode->i_state & I_LOCK) 1081da177e4SLinus Torvalds goto out; 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* 1111da177e4SLinus Torvalds * Only add valid (hashed) inodes to the superblock's 1121da177e4SLinus Torvalds * dirty list. Add blockdev inodes as well. 1131da177e4SLinus Torvalds */ 1141da177e4SLinus Torvalds if (!S_ISBLK(inode->i_mode)) { 1151da177e4SLinus Torvalds if (hlist_unhashed(&inode->i_hash)) 1161da177e4SLinus Torvalds goto out; 1171da177e4SLinus Torvalds } 1181da177e4SLinus Torvalds if (inode->i_state & (I_FREEING|I_CLEAR)) 1191da177e4SLinus Torvalds goto out; 1201da177e4SLinus Torvalds 1211da177e4SLinus Torvalds /* 1221da177e4SLinus Torvalds * If the inode was already on s_dirty or s_io, don't 1231da177e4SLinus Torvalds * reposition it (that would break s_dirty time-ordering). 1241da177e4SLinus Torvalds */ 1251da177e4SLinus Torvalds if (!was_dirty) { 1261da177e4SLinus Torvalds inode->dirtied_when = jiffies; 1271da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds out: 1311da177e4SLinus Torvalds spin_unlock(&inode_lock); 1321da177e4SLinus Torvalds } 1331da177e4SLinus Torvalds 1341da177e4SLinus Torvalds EXPORT_SYMBOL(__mark_inode_dirty); 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds static int write_inode(struct inode *inode, int sync) 1371da177e4SLinus Torvalds { 1381da177e4SLinus Torvalds if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) 1391da177e4SLinus Torvalds return inode->i_sb->s_op->write_inode(inode, sync); 1401da177e4SLinus Torvalds return 0; 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds /* 1441da177e4SLinus Torvalds * Write a single inode's dirty pages and inode data out to disk. 1451da177e4SLinus Torvalds * If `wait' is set, wait on the writeout. 1461da177e4SLinus Torvalds * 1471da177e4SLinus Torvalds * The whole writeout design is quite complex and fragile. We want to avoid 1481da177e4SLinus Torvalds * starvation of particular inodes when others are being redirtied, prevent 1491da177e4SLinus Torvalds * livelocks, etc. 1501da177e4SLinus Torvalds * 1511da177e4SLinus Torvalds * Called under inode_lock. 1521da177e4SLinus Torvalds */ 1531da177e4SLinus Torvalds static int 1541da177e4SLinus Torvalds __sync_single_inode(struct inode *inode, struct writeback_control *wbc) 1551da177e4SLinus Torvalds { 1561da177e4SLinus Torvalds unsigned dirty; 1571da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 1581da177e4SLinus Torvalds struct super_block *sb = inode->i_sb; 1591da177e4SLinus Torvalds int wait = wbc->sync_mode == WB_SYNC_ALL; 1601da177e4SLinus Torvalds int ret; 1611da177e4SLinus Torvalds 1621da177e4SLinus Torvalds BUG_ON(inode->i_state & I_LOCK); 1631da177e4SLinus Torvalds 1641da177e4SLinus Torvalds /* Set I_LOCK, reset I_DIRTY */ 1651da177e4SLinus Torvalds dirty = inode->i_state & I_DIRTY; 1661da177e4SLinus Torvalds inode->i_state |= I_LOCK; 1671da177e4SLinus Torvalds inode->i_state &= ~I_DIRTY; 1681da177e4SLinus Torvalds 1691da177e4SLinus Torvalds spin_unlock(&inode_lock); 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 1721da177e4SLinus Torvalds 1731da177e4SLinus Torvalds /* Don't write the inode if only I_DIRTY_PAGES was set */ 1741da177e4SLinus Torvalds if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 1751da177e4SLinus Torvalds int err = write_inode(inode, wait); 1761da177e4SLinus Torvalds if (ret == 0) 1771da177e4SLinus Torvalds ret = err; 1781da177e4SLinus Torvalds } 1791da177e4SLinus Torvalds 1801da177e4SLinus Torvalds if (wait) { 1811da177e4SLinus Torvalds int err = filemap_fdatawait(mapping); 1821da177e4SLinus Torvalds if (ret == 0) 1831da177e4SLinus Torvalds ret = err; 1841da177e4SLinus Torvalds } 1851da177e4SLinus Torvalds 1861da177e4SLinus Torvalds spin_lock(&inode_lock); 1871da177e4SLinus Torvalds inode->i_state &= ~I_LOCK; 1881da177e4SLinus Torvalds if (!(inode->i_state & I_FREEING)) { 1891da177e4SLinus Torvalds if (!(inode->i_state & I_DIRTY) && 1901da177e4SLinus Torvalds mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { 1911da177e4SLinus Torvalds /* 1921da177e4SLinus Torvalds * We didn't write back all the pages. nfs_writepages() 1931da177e4SLinus Torvalds * sometimes bales out without doing anything. Redirty 1941da177e4SLinus Torvalds * the inode. It is still on sb->s_io. 1951da177e4SLinus Torvalds */ 1961da177e4SLinus Torvalds if (wbc->for_kupdate) { 1971da177e4SLinus Torvalds /* 1981da177e4SLinus Torvalds * For the kupdate function we leave the inode 1991da177e4SLinus Torvalds * at the head of sb_dirty so it will get more 2001da177e4SLinus Torvalds * writeout as soon as the queue becomes 2011da177e4SLinus Torvalds * uncongested. 2021da177e4SLinus Torvalds */ 2031da177e4SLinus Torvalds inode->i_state |= I_DIRTY_PAGES; 2041da177e4SLinus Torvalds list_move_tail(&inode->i_list, &sb->s_dirty); 2051da177e4SLinus Torvalds } else { 2061da177e4SLinus Torvalds /* 2071da177e4SLinus Torvalds * Otherwise fully redirty the inode so that 2081da177e4SLinus Torvalds * other inodes on this superblock will get some 2091da177e4SLinus Torvalds * writeout. Otherwise heavy writing to one 2101da177e4SLinus Torvalds * file would indefinitely suspend writeout of 2111da177e4SLinus Torvalds * all the other files. 2121da177e4SLinus Torvalds */ 2131da177e4SLinus Torvalds inode->i_state |= I_DIRTY_PAGES; 2141da177e4SLinus Torvalds inode->dirtied_when = jiffies; 2151da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 2161da177e4SLinus Torvalds } 2171da177e4SLinus Torvalds } else if (inode->i_state & I_DIRTY) { 2181da177e4SLinus Torvalds /* 2191da177e4SLinus Torvalds * Someone redirtied the inode while were writing back 2201da177e4SLinus Torvalds * the pages. 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 2231da177e4SLinus Torvalds } else if (atomic_read(&inode->i_count)) { 2241da177e4SLinus Torvalds /* 2251da177e4SLinus Torvalds * The inode is clean, inuse 2261da177e4SLinus Torvalds */ 2271da177e4SLinus Torvalds list_move(&inode->i_list, &inode_in_use); 2281da177e4SLinus Torvalds } else { 2291da177e4SLinus Torvalds /* 2301da177e4SLinus Torvalds * The inode is clean, unused 2311da177e4SLinus Torvalds */ 2321da177e4SLinus Torvalds list_move(&inode->i_list, &inode_unused); 2331da177e4SLinus Torvalds } 2341da177e4SLinus Torvalds } 2351da177e4SLinus Torvalds wake_up_inode(inode); 2361da177e4SLinus Torvalds return ret; 2371da177e4SLinus Torvalds } 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds /* 2407f04c26dSAndrea Arcangeli * Write out an inode's dirty pages. Called under inode_lock. Either the 2417f04c26dSAndrea Arcangeli * caller has ref on the inode (either via __iget or via syscall against an fd) 2427f04c26dSAndrea Arcangeli * or the inode has I_WILL_FREE set (via generic_forget_inode) 2431da177e4SLinus Torvalds */ 2441da177e4SLinus Torvalds static int 2457f04c26dSAndrea Arcangeli __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 2461da177e4SLinus Torvalds { 2471da177e4SLinus Torvalds wait_queue_head_t *wqh; 2481da177e4SLinus Torvalds 2497f04c26dSAndrea Arcangeli if (!atomic_read(&inode->i_count)) 250659603efSAndrea Arcangeli WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 2517f04c26dSAndrea Arcangeli else 2527f04c26dSAndrea Arcangeli WARN_ON(inode->i_state & I_WILL_FREE); 2537f04c26dSAndrea Arcangeli 2541da177e4SLinus Torvalds if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) { 2551da177e4SLinus Torvalds list_move(&inode->i_list, &inode->i_sb->s_dirty); 2561da177e4SLinus Torvalds return 0; 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* 2601da177e4SLinus Torvalds * It's a data-integrity sync. We must wait. 2611da177e4SLinus Torvalds */ 2621da177e4SLinus Torvalds if (inode->i_state & I_LOCK) { 2631da177e4SLinus Torvalds DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK); 2641da177e4SLinus Torvalds 2651da177e4SLinus Torvalds wqh = bit_waitqueue(&inode->i_state, __I_LOCK); 2661da177e4SLinus Torvalds do { 2671da177e4SLinus Torvalds spin_unlock(&inode_lock); 2681da177e4SLinus Torvalds __wait_on_bit(wqh, &wq, inode_wait, 2691da177e4SLinus Torvalds TASK_UNINTERRUPTIBLE); 2701da177e4SLinus Torvalds spin_lock(&inode_lock); 2711da177e4SLinus Torvalds } while (inode->i_state & I_LOCK); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds return __sync_single_inode(inode, wbc); 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* 2771da177e4SLinus Torvalds * Write out a superblock's list of dirty inodes. A wait will be performed 2781da177e4SLinus Torvalds * upon no inodes, all inodes or the final one, depending upon sync_mode. 2791da177e4SLinus Torvalds * 2801da177e4SLinus Torvalds * If older_than_this is non-NULL, then only write out inodes which 2811da177e4SLinus Torvalds * had their first dirtying at a time earlier than *older_than_this. 2821da177e4SLinus Torvalds * 2831da177e4SLinus Torvalds * If we're a pdlfush thread, then implement pdflush collision avoidance 2841da177e4SLinus Torvalds * against the entire list. 2851da177e4SLinus Torvalds * 2861da177e4SLinus Torvalds * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so 2871da177e4SLinus Torvalds * that it can be located for waiting on in __writeback_single_inode(). 2881da177e4SLinus Torvalds * 2891da177e4SLinus Torvalds * Called under inode_lock. 2901da177e4SLinus Torvalds * 2911da177e4SLinus Torvalds * If `bdi' is non-zero then we're being asked to writeback a specific queue. 2921da177e4SLinus Torvalds * This function assumes that the blockdev superblock's inodes are backed by 2931da177e4SLinus Torvalds * a variety of queues, so all inodes are searched. For other superblocks, 2941da177e4SLinus Torvalds * assume that all inodes are backed by the same queue. 2951da177e4SLinus Torvalds * 2961da177e4SLinus Torvalds * FIXME: this linear search could get expensive with many fileystems. But 2971da177e4SLinus Torvalds * how to fix? We need to go from an address_space to all inodes which share 2981da177e4SLinus Torvalds * a queue with that address_space. (Easy: have a global "dirty superblocks" 2991da177e4SLinus Torvalds * list). 3001da177e4SLinus Torvalds * 3011da177e4SLinus Torvalds * The inodes to be written are parked on sb->s_io. They are moved back onto 3021da177e4SLinus Torvalds * sb->s_dirty as they are selected for writing. This way, none can be missed 3031da177e4SLinus Torvalds * on the writer throttling path, and we get decent balancing between many 3041da177e4SLinus Torvalds * throttled threads: we don't want them all piling up on __wait_on_inode. 3051da177e4SLinus Torvalds */ 3061da177e4SLinus Torvalds static void 3071da177e4SLinus Torvalds sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc) 3081da177e4SLinus Torvalds { 3091da177e4SLinus Torvalds const unsigned long start = jiffies; /* livelock avoidance */ 3101da177e4SLinus Torvalds 3111da177e4SLinus Torvalds if (!wbc->for_kupdate || list_empty(&sb->s_io)) 3121da177e4SLinus Torvalds list_splice_init(&sb->s_dirty, &sb->s_io); 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds while (!list_empty(&sb->s_io)) { 3151da177e4SLinus Torvalds struct inode *inode = list_entry(sb->s_io.prev, 3161da177e4SLinus Torvalds struct inode, i_list); 3171da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 3181da177e4SLinus Torvalds struct backing_dev_info *bdi = mapping->backing_dev_info; 3191da177e4SLinus Torvalds long pages_skipped; 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds if (!bdi_cap_writeback_dirty(bdi)) { 3221da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 3231da177e4SLinus Torvalds if (sb == blockdev_superblock) { 3241da177e4SLinus Torvalds /* 3251da177e4SLinus Torvalds * Dirty memory-backed blockdev: the ramdisk 3261da177e4SLinus Torvalds * driver does this. Skip just this inode 3271da177e4SLinus Torvalds */ 3281da177e4SLinus Torvalds continue; 3291da177e4SLinus Torvalds } 3301da177e4SLinus Torvalds /* 3311da177e4SLinus Torvalds * Dirty memory-backed inode against a filesystem other 3321da177e4SLinus Torvalds * than the kernel-internal bdev filesystem. Skip the 3331da177e4SLinus Torvalds * entire superblock. 3341da177e4SLinus Torvalds */ 3351da177e4SLinus Torvalds break; 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds 3381da177e4SLinus Torvalds if (wbc->nonblocking && bdi_write_congested(bdi)) { 3391da177e4SLinus Torvalds wbc->encountered_congestion = 1; 3401da177e4SLinus Torvalds if (sb != blockdev_superblock) 3411da177e4SLinus Torvalds break; /* Skip a congested fs */ 3421da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 3431da177e4SLinus Torvalds continue; /* Skip a congested blockdev */ 3441da177e4SLinus Torvalds } 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds if (wbc->bdi && bdi != wbc->bdi) { 3471da177e4SLinus Torvalds if (sb != blockdev_superblock) 3481da177e4SLinus Torvalds break; /* fs has the wrong queue */ 3491da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 3501da177e4SLinus Torvalds continue; /* blockdev has wrong queue */ 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds /* Was this inode dirtied after sync_sb_inodes was called? */ 3541da177e4SLinus Torvalds if (time_after(inode->dirtied_when, start)) 3551da177e4SLinus Torvalds break; 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds /* Was this inode dirtied too recently? */ 3581da177e4SLinus Torvalds if (wbc->older_than_this && time_after(inode->dirtied_when, 3591da177e4SLinus Torvalds *wbc->older_than_this)) 3601da177e4SLinus Torvalds break; 3611da177e4SLinus Torvalds 3621da177e4SLinus Torvalds /* Is another pdflush already flushing this queue? */ 3631da177e4SLinus Torvalds if (current_is_pdflush() && !writeback_acquire(bdi)) 3641da177e4SLinus Torvalds break; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds BUG_ON(inode->i_state & I_FREEING); 3671da177e4SLinus Torvalds __iget(inode); 3681da177e4SLinus Torvalds pages_skipped = wbc->pages_skipped; 3691da177e4SLinus Torvalds __writeback_single_inode(inode, wbc); 3701da177e4SLinus Torvalds if (wbc->sync_mode == WB_SYNC_HOLD) { 3711da177e4SLinus Torvalds inode->dirtied_when = jiffies; 3721da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 3731da177e4SLinus Torvalds } 3741da177e4SLinus Torvalds if (current_is_pdflush()) 3751da177e4SLinus Torvalds writeback_release(bdi); 3761da177e4SLinus Torvalds if (wbc->pages_skipped != pages_skipped) { 3771da177e4SLinus Torvalds /* 3781da177e4SLinus Torvalds * writeback is not making progress due to locked 3791da177e4SLinus Torvalds * buffers. Skip this inode for now. 3801da177e4SLinus Torvalds */ 3811da177e4SLinus Torvalds list_move(&inode->i_list, &sb->s_dirty); 3821da177e4SLinus Torvalds } 3831da177e4SLinus Torvalds spin_unlock(&inode_lock); 3841da177e4SLinus Torvalds cond_resched(); 3851da177e4SLinus Torvalds iput(inode); 3861da177e4SLinus Torvalds spin_lock(&inode_lock); 3871da177e4SLinus Torvalds if (wbc->nr_to_write <= 0) 3881da177e4SLinus Torvalds break; 3891da177e4SLinus Torvalds } 3901da177e4SLinus Torvalds return; /* Leave any unwritten inodes on s_io */ 3911da177e4SLinus Torvalds } 3921da177e4SLinus Torvalds 3931da177e4SLinus Torvalds /* 3941da177e4SLinus Torvalds * Start writeback of dirty pagecache data against all unlocked inodes. 3951da177e4SLinus Torvalds * 3961da177e4SLinus Torvalds * Note: 3971da177e4SLinus Torvalds * We don't need to grab a reference to superblock here. If it has non-empty 3981da177e4SLinus Torvalds * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed 3991da177e4SLinus Torvalds * past sync_inodes_sb() until both the ->s_dirty and ->s_io lists are 4001da177e4SLinus Torvalds * empty. Since __sync_single_inode() regains inode_lock before it finally moves 4011da177e4SLinus Torvalds * inode from superblock lists we are OK. 4021da177e4SLinus Torvalds * 4031da177e4SLinus Torvalds * If `older_than_this' is non-zero then only flush inodes which have a 4041da177e4SLinus Torvalds * flushtime older than *older_than_this. 4051da177e4SLinus Torvalds * 4061da177e4SLinus Torvalds * If `bdi' is non-zero then we will scan the first inode against each 4071da177e4SLinus Torvalds * superblock until we find the matching ones. One group will be the dirty 4081da177e4SLinus Torvalds * inodes against a filesystem. Then when we hit the dummy blockdev superblock, 4091da177e4SLinus Torvalds * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not 4101da177e4SLinus Torvalds * super-efficient but we're about to do a ton of I/O... 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds void 4131da177e4SLinus Torvalds writeback_inodes(struct writeback_control *wbc) 4141da177e4SLinus Torvalds { 4151da177e4SLinus Torvalds struct super_block *sb; 4161da177e4SLinus Torvalds 4171da177e4SLinus Torvalds might_sleep(); 4181da177e4SLinus Torvalds spin_lock(&sb_lock); 4191da177e4SLinus Torvalds restart: 4201da177e4SLinus Torvalds sb = sb_entry(super_blocks.prev); 4211da177e4SLinus Torvalds for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { 4221da177e4SLinus Torvalds if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) { 4231da177e4SLinus Torvalds /* we're making our own get_super here */ 4241da177e4SLinus Torvalds sb->s_count++; 4251da177e4SLinus Torvalds spin_unlock(&sb_lock); 4261da177e4SLinus Torvalds /* 4271da177e4SLinus Torvalds * If we can't get the readlock, there's no sense in 4281da177e4SLinus Torvalds * waiting around, most of the time the FS is going to 4291da177e4SLinus Torvalds * be unmounted by the time it is released. 4301da177e4SLinus Torvalds */ 4311da177e4SLinus Torvalds if (down_read_trylock(&sb->s_umount)) { 4321da177e4SLinus Torvalds if (sb->s_root) { 4331da177e4SLinus Torvalds spin_lock(&inode_lock); 4341da177e4SLinus Torvalds sync_sb_inodes(sb, wbc); 4351da177e4SLinus Torvalds spin_unlock(&inode_lock); 4361da177e4SLinus Torvalds } 4371da177e4SLinus Torvalds up_read(&sb->s_umount); 4381da177e4SLinus Torvalds } 4391da177e4SLinus Torvalds spin_lock(&sb_lock); 4401da177e4SLinus Torvalds if (__put_super_and_need_restart(sb)) 4411da177e4SLinus Torvalds goto restart; 4421da177e4SLinus Torvalds } 4431da177e4SLinus Torvalds if (wbc->nr_to_write <= 0) 4441da177e4SLinus Torvalds break; 4451da177e4SLinus Torvalds } 4461da177e4SLinus Torvalds spin_unlock(&sb_lock); 4471da177e4SLinus Torvalds } 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds /* 4501da177e4SLinus Torvalds * writeback and wait upon the filesystem's dirty inodes. The caller will 4511da177e4SLinus Torvalds * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is 4521da177e4SLinus Torvalds * used to park the written inodes on sb->s_dirty for the wait pass. 4531da177e4SLinus Torvalds * 4541da177e4SLinus Torvalds * A finite limit is set on the number of pages which will be written. 4551da177e4SLinus Torvalds * To prevent infinite livelock of sys_sync(). 4561da177e4SLinus Torvalds * 4571da177e4SLinus Torvalds * We add in the number of potentially dirty inodes, because each inode write 4581da177e4SLinus Torvalds * can dirty pagecache in the underlying blockdev. 4591da177e4SLinus Torvalds */ 4601da177e4SLinus Torvalds void sync_inodes_sb(struct super_block *sb, int wait) 4611da177e4SLinus Torvalds { 4621da177e4SLinus Torvalds struct writeback_control wbc = { 4631da177e4SLinus Torvalds .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, 4641da177e4SLinus Torvalds }; 4651da177e4SLinus Torvalds unsigned long nr_dirty = read_page_state(nr_dirty); 4661da177e4SLinus Torvalds unsigned long nr_unstable = read_page_state(nr_unstable); 4671da177e4SLinus Torvalds 4681da177e4SLinus Torvalds wbc.nr_to_write = nr_dirty + nr_unstable + 4691da177e4SLinus Torvalds (inodes_stat.nr_inodes - inodes_stat.nr_unused) + 4701da177e4SLinus Torvalds nr_dirty + nr_unstable; 4711da177e4SLinus Torvalds wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ 4721da177e4SLinus Torvalds spin_lock(&inode_lock); 4731da177e4SLinus Torvalds sync_sb_inodes(sb, &wbc); 4741da177e4SLinus Torvalds spin_unlock(&inode_lock); 4751da177e4SLinus Torvalds } 4761da177e4SLinus Torvalds 4771da177e4SLinus Torvalds /* 4781da177e4SLinus Torvalds * Rather lame livelock avoidance. 4791da177e4SLinus Torvalds */ 4801da177e4SLinus Torvalds static void set_sb_syncing(int val) 4811da177e4SLinus Torvalds { 4821da177e4SLinus Torvalds struct super_block *sb; 4831da177e4SLinus Torvalds spin_lock(&sb_lock); 4841da177e4SLinus Torvalds sb = sb_entry(super_blocks.prev); 4851da177e4SLinus Torvalds for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { 4861da177e4SLinus Torvalds sb->s_syncing = val; 4871da177e4SLinus Torvalds } 4881da177e4SLinus Torvalds spin_unlock(&sb_lock); 4891da177e4SLinus Torvalds } 4901da177e4SLinus Torvalds 4911da177e4SLinus Torvalds /** 49267be2dd1SMartin Waitz * sync_inodes - writes all inodes to disk 49367be2dd1SMartin Waitz * @wait: wait for completion 4941da177e4SLinus Torvalds * 4951da177e4SLinus Torvalds * sync_inodes() goes through each super block's dirty inode list, writes the 4961da177e4SLinus Torvalds * inodes out, waits on the writeout and puts the inodes back on the normal 4971da177e4SLinus Torvalds * list. 4981da177e4SLinus Torvalds * 4991da177e4SLinus Torvalds * This is for sys_sync(). fsync_dev() uses the same algorithm. The subtle 5001da177e4SLinus Torvalds * part of the sync functions is that the blockdev "superblock" is processed 5011da177e4SLinus Torvalds * last. This is because the write_inode() function of a typical fs will 5021da177e4SLinus Torvalds * perform no I/O, but will mark buffers in the blockdev mapping as dirty. 5031da177e4SLinus Torvalds * What we want to do is to perform all that dirtying first, and then write 5041da177e4SLinus Torvalds * back all those inode blocks via the blockdev mapping in one sweep. So the 5051da177e4SLinus Torvalds * additional (somewhat redundant) sync_blockdev() calls here are to make 5061da177e4SLinus Torvalds * sure that really happens. Because if we call sync_inodes_sb(wait=1) with 5071da177e4SLinus Torvalds * outstanding dirty inodes, the writeback goes block-at-a-time within the 5081da177e4SLinus Torvalds * filesystem's write_inode(). This is extremely slow. 5091da177e4SLinus Torvalds */ 510618f0636SKirill Korotaev static void __sync_inodes(int wait) 5111da177e4SLinus Torvalds { 5121da177e4SLinus Torvalds struct super_block *sb; 5131da177e4SLinus Torvalds 514618f0636SKirill Korotaev spin_lock(&sb_lock); 515618f0636SKirill Korotaev restart: 516618f0636SKirill Korotaev list_for_each_entry(sb, &super_blocks, s_list) { 517618f0636SKirill Korotaev if (sb->s_syncing) 518618f0636SKirill Korotaev continue; 519618f0636SKirill Korotaev sb->s_syncing = 1; 520618f0636SKirill Korotaev sb->s_count++; 521618f0636SKirill Korotaev spin_unlock(&sb_lock); 522618f0636SKirill Korotaev down_read(&sb->s_umount); 523618f0636SKirill Korotaev if (sb->s_root) { 524618f0636SKirill Korotaev sync_inodes_sb(sb, wait); 5251da177e4SLinus Torvalds sync_blockdev(sb->s_bdev); 5261da177e4SLinus Torvalds } 527618f0636SKirill Korotaev up_read(&sb->s_umount); 528618f0636SKirill Korotaev spin_lock(&sb_lock); 529618f0636SKirill Korotaev if (__put_super_and_need_restart(sb)) 530618f0636SKirill Korotaev goto restart; 531618f0636SKirill Korotaev } 532618f0636SKirill Korotaev spin_unlock(&sb_lock); 533618f0636SKirill Korotaev } 534618f0636SKirill Korotaev 535618f0636SKirill Korotaev void sync_inodes(int wait) 536618f0636SKirill Korotaev { 537618f0636SKirill Korotaev set_sb_syncing(0); 538618f0636SKirill Korotaev __sync_inodes(0); 539618f0636SKirill Korotaev 5401da177e4SLinus Torvalds if (wait) { 5411da177e4SLinus Torvalds set_sb_syncing(0); 542618f0636SKirill Korotaev __sync_inodes(1); 5431da177e4SLinus Torvalds } 5441da177e4SLinus Torvalds } 5451da177e4SLinus Torvalds 5461da177e4SLinus Torvalds /** 5471da177e4SLinus Torvalds * write_inode_now - write an inode to disk 5481da177e4SLinus Torvalds * @inode: inode to write to disk 5491da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 5501da177e4SLinus Torvalds * 5517f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 5527f04c26dSAndrea Arcangeli * primarily needed by knfsd. 5537f04c26dSAndrea Arcangeli * 5547f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 5551da177e4SLinus Torvalds */ 5561da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 5571da177e4SLinus Torvalds { 5581da177e4SLinus Torvalds int ret; 5591da177e4SLinus Torvalds struct writeback_control wbc = { 5601da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 5611da177e4SLinus Torvalds .sync_mode = WB_SYNC_ALL, 5621da177e4SLinus Torvalds }; 5631da177e4SLinus Torvalds 5641da177e4SLinus Torvalds if (!mapping_cap_writeback_dirty(inode->i_mapping)) 56549364ce2SAndrew Morton wbc.nr_to_write = 0; 5661da177e4SLinus Torvalds 5671da177e4SLinus Torvalds might_sleep(); 5681da177e4SLinus Torvalds spin_lock(&inode_lock); 5691da177e4SLinus Torvalds ret = __writeback_single_inode(inode, &wbc); 5701da177e4SLinus Torvalds spin_unlock(&inode_lock); 5711da177e4SLinus Torvalds if (sync) 5721da177e4SLinus Torvalds wait_on_inode(inode); 5731da177e4SLinus Torvalds return ret; 5741da177e4SLinus Torvalds } 5751da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 5761da177e4SLinus Torvalds 5771da177e4SLinus Torvalds /** 5781da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 5791da177e4SLinus Torvalds * @inode: the inode to sync 5801da177e4SLinus Torvalds * @wbc: controls the writeback mode 5811da177e4SLinus Torvalds * 5821da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 5831da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 5841da177e4SLinus Torvalds * update inode->i_state. 5851da177e4SLinus Torvalds * 5861da177e4SLinus Torvalds * The caller must have a ref on the inode. 5871da177e4SLinus Torvalds */ 5881da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 5891da177e4SLinus Torvalds { 5901da177e4SLinus Torvalds int ret; 5911da177e4SLinus Torvalds 5921da177e4SLinus Torvalds spin_lock(&inode_lock); 5931da177e4SLinus Torvalds ret = __writeback_single_inode(inode, wbc); 5941da177e4SLinus Torvalds spin_unlock(&inode_lock); 5951da177e4SLinus Torvalds return ret; 5961da177e4SLinus Torvalds } 5971da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 5981da177e4SLinus Torvalds 5991da177e4SLinus Torvalds /** 6001da177e4SLinus Torvalds * generic_osync_inode - flush all dirty data for a given inode to disk 6011da177e4SLinus Torvalds * @inode: inode to write 60267be2dd1SMartin Waitz * @mapping: the address_space that should be flushed 6031da177e4SLinus Torvalds * @what: what to write and wait upon 6041da177e4SLinus Torvalds * 6051da177e4SLinus Torvalds * This can be called by file_write functions for files which have the 6061da177e4SLinus Torvalds * O_SYNC flag set, to flush dirty writes to disk. 6071da177e4SLinus Torvalds * 6081da177e4SLinus Torvalds * @what is a bitmask, specifying which part of the inode's data should be 6091da177e4SLinus Torvalds * written and waited upon: 6101da177e4SLinus Torvalds * 6111da177e4SLinus Torvalds * OSYNC_DATA: i_mapping's dirty data 6121da177e4SLinus Torvalds * OSYNC_METADATA: the buffers at i_mapping->private_list 6131da177e4SLinus Torvalds * OSYNC_INODE: the inode itself 6141da177e4SLinus Torvalds */ 6151da177e4SLinus Torvalds 6161da177e4SLinus Torvalds int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) 6171da177e4SLinus Torvalds { 6181da177e4SLinus Torvalds int err = 0; 6191da177e4SLinus Torvalds int need_write_inode_now = 0; 6201da177e4SLinus Torvalds int err2; 6211da177e4SLinus Torvalds 6221da177e4SLinus Torvalds current->flags |= PF_SYNCWRITE; 6231da177e4SLinus Torvalds if (what & OSYNC_DATA) 6241da177e4SLinus Torvalds err = filemap_fdatawrite(mapping); 6251da177e4SLinus Torvalds if (what & (OSYNC_METADATA|OSYNC_DATA)) { 6261da177e4SLinus Torvalds err2 = sync_mapping_buffers(mapping); 6271da177e4SLinus Torvalds if (!err) 6281da177e4SLinus Torvalds err = err2; 6291da177e4SLinus Torvalds } 6301da177e4SLinus Torvalds if (what & OSYNC_DATA) { 6311da177e4SLinus Torvalds err2 = filemap_fdatawait(mapping); 6321da177e4SLinus Torvalds if (!err) 6331da177e4SLinus Torvalds err = err2; 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds current->flags &= ~PF_SYNCWRITE; 6361da177e4SLinus Torvalds 6371da177e4SLinus Torvalds spin_lock(&inode_lock); 6381da177e4SLinus Torvalds if ((inode->i_state & I_DIRTY) && 6391da177e4SLinus Torvalds ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) 6401da177e4SLinus Torvalds need_write_inode_now = 1; 6411da177e4SLinus Torvalds spin_unlock(&inode_lock); 6421da177e4SLinus Torvalds 6431da177e4SLinus Torvalds if (need_write_inode_now) { 6441da177e4SLinus Torvalds err2 = write_inode_now(inode, 1); 6451da177e4SLinus Torvalds if (!err) 6461da177e4SLinus Torvalds err = err2; 6471da177e4SLinus Torvalds } 6481da177e4SLinus Torvalds else 6491da177e4SLinus Torvalds wait_on_inode(inode); 6501da177e4SLinus Torvalds 6511da177e4SLinus Torvalds return err; 6521da177e4SLinus Torvalds } 6531da177e4SLinus Torvalds 6541da177e4SLinus Torvalds EXPORT_SYMBOL(generic_osync_inode); 6551da177e4SLinus Torvalds 6561da177e4SLinus Torvalds /** 6571da177e4SLinus Torvalds * writeback_acquire: attempt to get exclusive writeback access to a device 6581da177e4SLinus Torvalds * @bdi: the device's backing_dev_info structure 6591da177e4SLinus Torvalds * 6601da177e4SLinus Torvalds * It is a waste of resources to have more than one pdflush thread blocked on 6611da177e4SLinus Torvalds * a single request queue. Exclusion at the request_queue level is obtained 6621da177e4SLinus Torvalds * via a flag in the request_queue's backing_dev_info.state. 6631da177e4SLinus Torvalds * 6641da177e4SLinus Torvalds * Non-request_queue-backed address_spaces will share default_backing_dev_info, 6651da177e4SLinus Torvalds * unless they implement their own. Which is somewhat inefficient, as this 6661da177e4SLinus Torvalds * may prevent concurrent writeback against multiple devices. 6671da177e4SLinus Torvalds */ 6681da177e4SLinus Torvalds int writeback_acquire(struct backing_dev_info *bdi) 6691da177e4SLinus Torvalds { 6701da177e4SLinus Torvalds return !test_and_set_bit(BDI_pdflush, &bdi->state); 6711da177e4SLinus Torvalds } 6721da177e4SLinus Torvalds 6731da177e4SLinus Torvalds /** 6741da177e4SLinus Torvalds * writeback_in_progress: determine whether there is writeback in progress 6751da177e4SLinus Torvalds * against a backing device. 6761da177e4SLinus Torvalds * @bdi: the device's backing_dev_info structure. 6771da177e4SLinus Torvalds */ 6781da177e4SLinus Torvalds int writeback_in_progress(struct backing_dev_info *bdi) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds return test_bit(BDI_pdflush, &bdi->state); 6811da177e4SLinus Torvalds } 6821da177e4SLinus Torvalds 6831da177e4SLinus Torvalds /** 6841da177e4SLinus Torvalds * writeback_release: relinquish exclusive writeback access against a device. 6851da177e4SLinus Torvalds * @bdi: the device's backing_dev_info structure 6861da177e4SLinus Torvalds */ 6871da177e4SLinus Torvalds void writeback_release(struct backing_dev_info *bdi) 6881da177e4SLinus Torvalds { 6891da177e4SLinus Torvalds BUG_ON(!writeback_in_progress(bdi)); 6901da177e4SLinus Torvalds clear_bit(BDI_pdflush, &bdi->state); 6911da177e4SLinus Torvalds } 692