// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2010 Red Hat, Inc. * Copyright (C) 2016-2019 Christoph Hellwig. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "trace.h" #include "../internal.h" /* * Structure allocated for each page or THP when block size < page size * to track sub-page uptodate status and I/O completions. */ struct iomap_page { atomic_t read_bytes_pending; atomic_t write_bytes_pending; spinlock_t uptodate_lock; unsigned long uptodate[]; }; static inline struct iomap_page *to_iomap_page(struct page *page) { /* * per-block data is stored in the head page. Callers should * not be dealing with tail pages (and if they are, they can * call thp_head() first. */ VM_BUG_ON_PGFLAGS(PageTail(page), page); if (page_has_private(page)) return (struct iomap_page *)page_private(page); return NULL; } static struct bio_set iomap_ioend_bioset; static struct iomap_page * iomap_page_create(struct inode *inode, struct page *page) { struct iomap_page *iop = to_iomap_page(page); unsigned int nr_blocks = i_blocks_per_page(inode, page); if (iop || nr_blocks <= 1) return iop; iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)), GFP_NOFS | __GFP_NOFAIL); spin_lock_init(&iop->uptodate_lock); if (PageUptodate(page)) bitmap_fill(iop->uptodate, nr_blocks); attach_page_private(page, iop); return iop; } static void iomap_page_release(struct page *page) { struct iomap_page *iop = detach_page_private(page); unsigned int nr_blocks = i_blocks_per_page(page->mapping->host, page); if (!iop) return; WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending)); WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending)); WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) != PageUptodate(page)); kfree(iop); } /* * Calculate the range inside the page that we actually need to read. */ static void iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop, loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp) { loff_t orig_pos = *pos; loff_t isize = i_size_read(inode); unsigned block_bits = inode->i_blkbits; unsigned block_size = (1 << block_bits); unsigned poff = offset_in_page(*pos); unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length); unsigned first = poff >> block_bits; unsigned last = (poff + plen - 1) >> block_bits; /* * If the block size is smaller than the page size we need to check the * per-block uptodate status and adjust the offset and length if needed * to avoid reading in already uptodate ranges. */ if (iop) { unsigned int i; /* move forward for each leading block marked uptodate */ for (i = first; i <= last; i++) { if (!test_bit(i, iop->uptodate)) break; *pos += block_size; poff += block_size; plen -= block_size; first++; } /* truncate len if we find any trailing uptodate block(s) */ for ( ; i <= last; i++) { if (test_bit(i, iop->uptodate)) { plen -= (last - i + 1) * block_size; last = i - 1; break; } } } /* * If the extent spans the block that contains the i_size we need to * handle both halves separately so that we properly zero data in the * page cache for blocks that are entirely outside of i_size. */ if (orig_pos <= isize && orig_pos + length > isize) { unsigned end = offset_in_page(isize - 1) >> block_bits; if (first <= end && last > end) plen -= (last - end) * block_size; } *offp = poff; *lenp = plen; } static void iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len) { struct iomap_page *iop = to_iomap_page(page); struct inode *inode = page->mapping->host; unsigned first = off >> inode->i_blkbits; unsigned last = (off + len - 1) >> inode->i_blkbits; unsigned long flags; spin_lock_irqsave(&iop->uptodate_lock, flags); bitmap_set(iop->uptodate, first, last - first + 1); if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page))) SetPageUptodate(page); spin_unlock_irqrestore(&iop->uptodate_lock, flags); } static void iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len) { if (PageError(page)) return; if (page_has_private(page)) iomap_iop_set_range_uptodate(page, off, len); else SetPageUptodate(page); } static void iomap_read_page_end_io(struct bio_vec *bvec, int error) { struct page *page = bvec->bv_page; struct iomap_page *iop = to_iomap_page(page); if (unlikely(error)) { ClearPageUptodate(page); SetPageError(page); } else { iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len); } if (!iop || atomic_sub_and_test(bvec->bv_len, &iop->read_bytes_pending)) unlock_page(page); } static void iomap_read_end_io(struct bio *bio) { int error = blk_status_to_errno(bio->bi_status); struct bio_vec *bvec; struct bvec_iter_all iter_all; bio_for_each_segment_all(bvec, bio, iter_all) iomap_read_page_end_io(bvec, error); bio_put(bio); } struct iomap_readpage_ctx { struct page *cur_page; bool cur_page_in_bio; struct bio *bio; struct readahead_control *rac; }; static void iomap_read_inline_data(struct inode *inode, struct page *page, struct iomap *iomap) { size_t size = i_size_read(inode); void *addr; if (PageUptodate(page)) return; BUG_ON(page_has_private(page)); BUG_ON(page->index); BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data)); addr = kmap_atomic(page); memcpy(addr, iomap->inline_data, size); memset(addr + size, 0, PAGE_SIZE - size); kunmap_atomic(addr); SetPageUptodate(page); } static inline bool iomap_block_needs_zeroing(struct inode *inode, struct iomap *iomap, loff_t pos) { return iomap->type != IOMAP_MAPPED || (iomap->flags & IOMAP_F_NEW) || pos >= i_size_read(inode); } static loff_t iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { struct iomap_readpage_ctx *ctx = data; struct page *page = ctx->cur_page; struct iomap_page *iop; loff_t orig_pos = pos; unsigned poff, plen; sector_t sector; if (iomap->type == IOMAP_INLINE) { WARN_ON_ONCE(pos); iomap_read_inline_data(inode, page, iomap); return PAGE_SIZE; } /* zero post-eof blocks as the page may be mapped */ iop = iomap_page_create(inode, page); iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); if (plen == 0) goto done; if (iomap_block_needs_zeroing(inode, iomap, pos)) { zero_user(page, poff, plen); iomap_set_range_uptodate(page, poff, plen); goto done; } ctx->cur_page_in_bio = true; if (iop) atomic_add(plen, &iop->read_bytes_pending); sector = iomap_sector(iomap, pos); if (!ctx->bio || bio_end_sector(ctx->bio) != sector || bio_add_page(ctx->bio, page, plen, poff) != plen) { gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); gfp_t orig_gfp = gfp; unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE); if (ctx->bio) submit_bio(ctx->bio); if (ctx->rac) /* same as readahead_gfp_mask */ gfp |= __GFP_NORETRY | __GFP_NOWARN; ctx->bio = bio_alloc(gfp, bio_max_segs(nr_vecs)); /* * If the bio_alloc fails, try it again for a single page to * avoid having to deal with partial page reads. This emulates * what do_mpage_readpage does. */ if (!ctx->bio) ctx->bio = bio_alloc(orig_gfp, 1); ctx->bio->bi_opf = REQ_OP_READ; if (ctx->rac) ctx->bio->bi_opf |= REQ_RAHEAD; ctx->bio->bi_iter.bi_sector = sector; bio_set_dev(ctx->bio, iomap->bdev); ctx->bio->bi_end_io = iomap_read_end_io; __bio_add_page(ctx->bio, page, plen, poff); } done: /* * Move the caller beyond our range so that it keeps making progress. * For that we have to include any leading non-uptodate ranges, but * we can skip trailing ones as they will be handled in the next * iteration. */ return pos - orig_pos + plen; } int iomap_readpage(struct page *page, const struct iomap_ops *ops) { struct iomap_readpage_ctx ctx = { .cur_page = page }; struct inode *inode = page->mapping->host; unsigned poff; loff_t ret; trace_iomap_readpage(page->mapping->host, 1); for (poff = 0; poff < PAGE_SIZE; poff += ret) { ret = iomap_apply(inode, page_offset(page) + poff, PAGE_SIZE - poff, 0, ops, &ctx, iomap_readpage_actor); if (ret <= 0) { WARN_ON_ONCE(ret == 0); SetPageError(page); break; } } if (ctx.bio) { submit_bio(ctx.bio); WARN_ON_ONCE(!ctx.cur_page_in_bio); } else { WARN_ON_ONCE(ctx.cur_page_in_bio); unlock_page(page); } /* * Just like mpage_readahead and block_read_full_page we always * return 0 and just mark the page as PageError on errors. This * should be cleaned up all through the stack eventually. */ return 0; } EXPORT_SYMBOL_GPL(iomap_readpage); static loff_t iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { struct iomap_readpage_ctx *ctx = data; loff_t done, ret; for (done = 0; done < length; done += ret) { if (ctx->cur_page && offset_in_page(pos + done) == 0) { if (!ctx->cur_page_in_bio) unlock_page(ctx->cur_page); put_page(ctx->cur_page); ctx->cur_page = NULL; } if (!ctx->cur_page) { ctx->cur_page = readahead_page(ctx->rac); ctx->cur_page_in_bio = false; } ret = iomap_readpage_actor(inode, pos + done, length - done, ctx, iomap, srcmap); } return done; } /** * iomap_readahead - Attempt to read pages from a file. * @rac: Describes the pages to be read. * @ops: The operations vector for the filesystem. * * This function is for filesystems to call to implement their readahead * address_space operation. * * Context: The @ops callbacks may submit I/O (eg to read the addresses of * blocks from disc), and may wait for it. The caller may be trying to * access a different page, and so sleeping excessively should be avoided. * It may allocate memory, but should avoid costly allocations. This * function is called with memalloc_nofs set, so allocations will not cause * the filesystem to be reentered. */ void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops) { struct inode *inode = rac->mapping->host; loff_t pos = readahead_pos(rac); size_t length = readahead_length(rac); struct iomap_readpage_ctx ctx = { .rac = rac, }; trace_iomap_readahead(inode, readahead_count(rac)); while (length > 0) { ssize_t ret = iomap_apply(inode, pos, length, 0, ops, &ctx, iomap_readahead_actor); if (ret <= 0) { WARN_ON_ONCE(ret == 0); break; } pos += ret; length -= ret; } if (ctx.bio) submit_bio(ctx.bio); if (ctx.cur_page) { if (!ctx.cur_page_in_bio) unlock_page(ctx.cur_page); put_page(ctx.cur_page); } } EXPORT_SYMBOL_GPL(iomap_readahead); /* * iomap_is_partially_uptodate checks whether blocks within a page are * uptodate or not. * * Returns true if all blocks which correspond to a file portion * we want to read within the page are uptodate. */ int iomap_is_partially_uptodate(struct page *page, unsigned long from, unsigned long count) { struct iomap_page *iop = to_iomap_page(page); struct inode *inode = page->mapping->host; unsigned len, first, last; unsigned i; /* Limit range to one page */ len = min_t(unsigned, PAGE_SIZE - from, count); /* First and last blocks in range within page */ first = from >> inode->i_blkbits; last = (from + len - 1) >> inode->i_blkbits; if (iop) { for (i = first; i <= last; i++) if (!test_bit(i, iop->uptodate)) return 0; return 1; } return 0; } EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate); int iomap_releasepage(struct page *page, gfp_t gfp_mask) { trace_iomap_releasepage(page->mapping->host, page_offset(page), PAGE_SIZE); /* * mm accommodates an old ext3 case where clean pages might not have had * the dirty bit cleared. Thus, it can send actual dirty pages to * ->releasepage() via shrink_active_list(), skip those here. */ if (PageDirty(page) || PageWriteback(page)) return 0; iomap_page_release(page); return 1; } EXPORT_SYMBOL_GPL(iomap_releasepage); void iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len) { trace_iomap_invalidatepage(page->mapping->host, offset, len); /* * If we are invalidating the entire page, clear the dirty state from it * and release it to avoid unnecessary buildup of the LRU. */ if (offset == 0 && len == PAGE_SIZE) { WARN_ON_ONCE(PageWriteback(page)); cancel_dirty_page(page); iomap_page_release(page); } } EXPORT_SYMBOL_GPL(iomap_invalidatepage); #ifdef CONFIG_MIGRATION int iomap_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page, enum migrate_mode mode) { int ret; ret = migrate_page_move_mapping(mapping, newpage, page, 0); if (ret != MIGRATEPAGE_SUCCESS) return ret; if (page_has_private(page)) attach_page_private(newpage, detach_page_private(page)); if (mode != MIGRATE_SYNC_NO_COPY) migrate_page_copy(newpage, page); else migrate_page_states(newpage, page); return MIGRATEPAGE_SUCCESS; } EXPORT_SYMBOL_GPL(iomap_migrate_page); #endif /* CONFIG_MIGRATION */ enum { IOMAP_WRITE_F_UNSHARE = (1 << 0), }; static void iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) { loff_t i_size = i_size_read(inode); /* * Only truncate newly allocated pages beyoned EOF, even if the * write started inside the existing inode size. */ if (pos + len > i_size) truncate_pagecache_range(inode, max(pos, i_size), pos + len); } static int iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff, unsigned plen, struct iomap *iomap) { struct bio_vec bvec; struct bio bio; bio_init(&bio, &bvec, 1); bio.bi_opf = REQ_OP_READ; bio.bi_iter.bi_sector = iomap_sector(iomap, block_start); bio_set_dev(&bio, iomap->bdev); __bio_add_page(&bio, page, plen, poff); return submit_bio_wait(&bio); } static int __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, struct page *page, struct iomap *srcmap) { struct iomap_page *iop = iomap_page_create(inode, page); loff_t block_size = i_blocksize(inode); loff_t block_start = round_down(pos, block_size); loff_t block_end = round_up(pos + len, block_size); unsigned from = offset_in_page(pos), to = from + len, poff, plen; if (PageUptodate(page)) return 0; ClearPageError(page); do { iomap_adjust_read_range(inode, iop, &block_start, block_end - block_start, &poff, &plen); if (plen == 0) break; if (!(flags & IOMAP_WRITE_F_UNSHARE) && (from <= poff || from >= poff + plen) && (to <= poff || to >= poff + plen)) continue; if (iomap_block_needs_zeroing(inode, srcmap, block_start)) { if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE)) return -EIO; zero_user_segments(page, poff, from, to, poff + plen); } else { int status = iomap_read_page_sync(block_start, page, poff, plen, srcmap); if (status) return status; } iomap_set_range_uptodate(page, poff, plen); } while ((block_start += plen) < block_end); return 0; } static int iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, struct page **pagep, struct iomap *iomap, struct iomap *srcmap) { const struct iomap_page_ops *page_ops = iomap->page_ops; struct page *page; int status = 0; BUG_ON(pos + len > iomap->offset + iomap->length); if (srcmap != iomap) BUG_ON(pos + len > srcmap->offset + srcmap->length); if (fatal_signal_pending(current)) return -EINTR; if (page_ops && page_ops->page_prepare) { status = page_ops->page_prepare(inode, pos, len, iomap); if (status) return status; } page = grab_cache_page_write_begin(inode->i_mapping, pos >> PAGE_SHIFT, AOP_FLAG_NOFS); if (!page) { status = -ENOMEM; goto out_no_page; } if (srcmap->type == IOMAP_INLINE) iomap_read_inline_data(inode, page, srcmap); else if (iomap->flags & IOMAP_F_BUFFER_HEAD) status = __block_write_begin_int(page, pos, len, NULL, srcmap); else status = __iomap_write_begin(inode, pos, len, flags, page, srcmap); if (unlikely(status)) goto out_unlock; *pagep = page; return 0; out_unlock: unlock_page(page); put_page(page); iomap_write_failed(inode, pos, len); out_no_page: if (page_ops && page_ops->page_done) page_ops->page_done(inode, pos, 0, NULL, iomap); return status; } static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len, size_t copied, struct page *page) { flush_dcache_page(page); /* * The blocks that were entirely written will now be uptodate, so we * don't have to worry about a readpage reading them and overwriting a * partial write. However if we have encountered a short write and only * partially written into a block, it will not be marked uptodate, so a * readpage might come in and destroy our partial write. * * Do the simplest thing, and just treat any short write to a non * uptodate page as a zero-length write, and force the caller to redo * the whole thing. */ if (unlikely(copied < len && !PageUptodate(page))) return 0; iomap_set_range_uptodate(page, offset_in_page(pos), len); __set_page_dirty_nobuffers(page); return copied; } static size_t iomap_write_end_inline(struct inode *inode, struct page *page, struct iomap *iomap, loff_t pos, size_t copied) { void *addr; WARN_ON_ONCE(!PageUptodate(page)); BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data)); flush_dcache_page(page); addr = kmap_atomic(page); memcpy(iomap->inline_data + pos, addr + pos, copied); kunmap_atomic(addr); mark_inode_dirty(inode); return copied; } /* Returns the number of bytes copied. May be 0. Cannot be an errno. */ static size_t iomap_write_end(struct inode *inode, loff_t pos, size_t len, size_t copied, struct page *page, struct iomap *iomap, struct iomap *srcmap) { const struct iomap_page_ops *page_ops = iomap->page_ops; loff_t old_size = inode->i_size; size_t ret; if (srcmap->type == IOMAP_INLINE) { ret = iomap_write_end_inline(inode, page, iomap, pos, copied); } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) { ret = block_write_end(NULL, inode->i_mapping, pos, len, copied, page, NULL); } else { ret = __iomap_write_end(inode, pos, len, copied, page); } /* * Update the in-memory inode size after copying the data into the page * cache. It's up to the file system to write the updated size to disk, * preferably after I/O completion so that no stale data is exposed. */ if (pos + ret > old_size) { i_size_write(inode, pos + ret); iomap->flags |= IOMAP_F_SIZE_CHANGED; } unlock_page(page); if (old_size < pos) pagecache_isize_extended(inode, old_size, pos); if (page_ops && page_ops->page_done) page_ops->page_done(inode, pos, ret, page, iomap); put_page(page); if (ret < len) iomap_write_failed(inode, pos, len); return ret; } static loff_t iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { struct iov_iter *i = data; long status = 0; ssize_t written = 0; do { struct page *page; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ offset = offset_in_page(pos); bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_count(i)); again: if (bytes > length) bytes = length; /* * Bring in the user page that we will copy from _first_. * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. */ if (unlikely(iov_iter_fault_in_readable(i, bytes))) { status = -EFAULT; break; } status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap); if (unlikely(status)) break; if (mapping_writably_mapped(inode->i_mapping)) flush_dcache_page(page); copied = copy_page_from_iter_atomic(page, offset, bytes, i); status = iomap_write_end(inode, pos, bytes, copied, page, iomap, srcmap); if (unlikely(copied != status)) iov_iter_revert(i, copied - status); cond_resched(); if (unlikely(status == 0)) { /* * A short copy made iomap_write_end() reject the * thing entirely. Might be memory poisoning * halfway through, might be a race with munmap, * might be severe memory pressure. */ if (copied) bytes = copied; goto again; } pos += status; written += status; length -= status; balance_dirty_pages_ratelimited(inode->i_mapping); } while (iov_iter_count(i) && length); return written ? written : status; } ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops) { struct inode *inode = iocb->ki_filp->f_mapping->host; loff_t pos = iocb->ki_pos, ret = 0, written = 0; while (iov_iter_count(iter)) { ret = iomap_apply(inode, pos, iov_iter_count(iter), IOMAP_WRITE, ops, iter, iomap_write_actor); if (ret <= 0) break; pos += ret; written += ret; } return written ? written : ret; } EXPORT_SYMBOL_GPL(iomap_file_buffered_write); static loff_t iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { long status = 0; loff_t written = 0; /* don't bother with blocks that are not shared to start with */ if (!(iomap->flags & IOMAP_F_SHARED)) return length; /* don't bother with holes or unwritten extents */ if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) return length; do { unsigned long offset = offset_in_page(pos); unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length); struct page *page; status = iomap_write_begin(inode, pos, bytes, IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap); if (unlikely(status)) return status; status = iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap); if (WARN_ON_ONCE(status == 0)) return -EIO; cond_resched(); pos += status; written += status; length -= status; balance_dirty_pages_ratelimited(inode->i_mapping); } while (length); return written; } int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len, const struct iomap_ops *ops) { loff_t ret; while (len) { ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL, iomap_unshare_actor); if (ret <= 0) return ret; pos += ret; len -= ret; } return 0; } EXPORT_SYMBOL_GPL(iomap_file_unshare); static s64 iomap_zero(struct inode *inode, loff_t pos, u64 length, struct iomap *iomap, struct iomap *srcmap) { struct page *page; int status; unsigned offset = offset_in_page(pos); unsigned bytes = min_t(u64, PAGE_SIZE - offset, length); status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap); if (status) return status; zero_user(page, offset, bytes); mark_page_accessed(page); return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap); } static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { bool *did_zero = data; loff_t written = 0; /* already zeroed? we're done. */ if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) return length; do { s64 bytes; if (IS_DAX(inode)) bytes = dax_iomap_zero(pos, length, iomap); else bytes = iomap_zero(inode, pos, length, iomap, srcmap); if (bytes < 0) return bytes; pos += bytes; length -= bytes; written += bytes; if (did_zero) *did_zero = true; } while (length > 0); return written; } int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, const struct iomap_ops *ops) { loff_t ret; while (len > 0) { ret = iomap_apply(inode, pos, len, IOMAP_ZERO, ops, did_zero, iomap_zero_range_actor); if (ret <= 0) return ret; pos += ret; len -= ret; } return 0; } EXPORT_SYMBOL_GPL(iomap_zero_range); int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, const struct iomap_ops *ops) { unsigned int blocksize = i_blocksize(inode); unsigned int off = pos & (blocksize - 1); /* Block boundary? Nothing to do */ if (!off) return 0; return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops); } EXPORT_SYMBOL_GPL(iomap_truncate_page); static loff_t iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { struct page *page = data; int ret; if (iomap->flags & IOMAP_F_BUFFER_HEAD) { ret = __block_write_begin_int(page, pos, length, NULL, iomap); if (ret) return ret; block_commit_write(page, 0, length); } else { WARN_ON_ONCE(!PageUptodate(page)); set_page_dirty(page); } return length; } vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) { struct page *page = vmf->page; struct inode *inode = file_inode(vmf->vma->vm_file); unsigned long length; loff_t offset; ssize_t ret; lock_page(page); ret = page_mkwrite_check_truncate(page, inode); if (ret < 0) goto out_unlock; length = ret; offset = page_offset(page); while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_WRITE | IOMAP_FAULT, ops, page, iomap_page_mkwrite_actor); if (unlikely(ret <= 0)) goto out_unlock; offset += ret; length -= ret; } wait_for_stable_page(page); return VM_FAULT_LOCKED; out_unlock: unlock_page(page); return block_page_mkwrite_return(ret); } EXPORT_SYMBOL_GPL(iomap_page_mkwrite); static void iomap_finish_page_writeback(struct inode *inode, struct page *page, int error, unsigned int len) { struct iomap_page *iop = to_iomap_page(page); if (error) { SetPageError(page); mapping_set_error(inode->i_mapping, -EIO); } WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop); WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) <= 0); if (!iop || atomic_sub_and_test(len, &iop->write_bytes_pending)) end_page_writeback(page); } /* * We're now finished for good with this ioend structure. Update the page * state, release holds on bios, and finally free up memory. Do not use the * ioend after this. */ static void iomap_finish_ioend(struct iomap_ioend *ioend, int error) { struct inode *inode = ioend->io_inode; struct bio *bio = &ioend->io_inline_bio; struct bio *last = ioend->io_bio, *next; u64 start = bio->bi_iter.bi_sector; loff_t offset = ioend->io_offset; bool quiet = bio_flagged(bio, BIO_QUIET); for (bio = &ioend->io_inline_bio; bio; bio = next) { struct bio_vec *bv; struct bvec_iter_all iter_all; /* * For the last bio, bi_private points to the ioend, so we * need to explicitly end the iteration here. */ if (bio == last) next = NULL; else next = bio->bi_private; /* walk each page on bio, ending page IO on them */ bio_for_each_segment_all(bv, bio, iter_all) iomap_finish_page_writeback(inode, bv->bv_page, error, bv->bv_len); bio_put(bio); } /* The ioend has been freed by bio_put() */ if (unlikely(error && !quiet)) { printk_ratelimited(KERN_ERR "%s: writeback error on inode %lu, offset %lld, sector %llu", inode->i_sb->s_id, inode->i_ino, offset, start); } } void iomap_finish_ioends(struct iomap_ioend *ioend, int error) { struct list_head tmp; list_replace_init(&ioend->io_list, &tmp); iomap_finish_ioend(ioend, error); while (!list_empty(&tmp)) { ioend = list_first_entry(&tmp, struct iomap_ioend, io_list); list_del_init(&ioend->io_list); iomap_finish_ioend(ioend, error); } } EXPORT_SYMBOL_GPL(iomap_finish_ioends); /* * We can merge two adjacent ioends if they have the same set of work to do. */ static bool iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next) { if (ioend->io_bio->bi_status != next->io_bio->bi_status) return false; if ((ioend->io_flags & IOMAP_F_SHARED) ^ (next->io_flags & IOMAP_F_SHARED)) return false; if ((ioend->io_type == IOMAP_UNWRITTEN) ^ (next->io_type == IOMAP_UNWRITTEN)) return false; if (ioend->io_offset + ioend->io_size != next->io_offset) return false; return true; } void iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends) { struct iomap_ioend *next; INIT_LIST_HEAD(&ioend->io_list); while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend, io_list))) { if (!iomap_ioend_can_merge(ioend, next)) break; list_move_tail(&next->io_list, &ioend->io_list); ioend->io_size += next->io_size; } } EXPORT_SYMBOL_GPL(iomap_ioend_try_merge); static int iomap_ioend_compare(void *priv, const struct list_head *a, const struct list_head *b) { struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list); struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list); if (ia->io_offset < ib->io_offset) return -1; if (ia->io_offset > ib->io_offset) return 1; return 0; } void iomap_sort_ioends(struct list_head *ioend_list) { list_sort(NULL, ioend_list, iomap_ioend_compare); } EXPORT_SYMBOL_GPL(iomap_sort_ioends); static void iomap_writepage_end_bio(struct bio *bio) { struct iomap_ioend *ioend = bio->bi_private; iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status)); } /* * Submit the final bio for an ioend. * * If @error is non-zero, it means that we have a situation where some part of * the submission process has failed after we have marked paged for writeback * and unlocked them. In this situation, we need to fail the bio instead of * submitting it. This typically only happens on a filesystem shutdown. */ static int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend, int error) { ioend->io_bio->bi_private = ioend; ioend->io_bio->bi_end_io = iomap_writepage_end_bio; if (wpc->ops->prepare_ioend) error = wpc->ops->prepare_ioend(ioend, error); if (error) { /* * If we are failing the IO now, just mark the ioend with an * error and finish it. This will run IO completion immediately * as there is only one reference to the ioend at this point in * time. */ ioend->io_bio->bi_status = errno_to_blk_status(error); bio_endio(ioend->io_bio); return error; } submit_bio(ioend->io_bio); return 0; } static struct iomap_ioend * iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc, loff_t offset, sector_t sector, struct writeback_control *wbc) { struct iomap_ioend *ioend; struct bio *bio; bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_VECS, &iomap_ioend_bioset); bio_set_dev(bio, wpc->iomap.bdev); bio->bi_iter.bi_sector = sector; bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); bio->bi_write_hint = inode->i_write_hint; wbc_init_bio(wbc, bio); ioend = container_of(bio, struct iomap_ioend, io_inline_bio); INIT_LIST_HEAD(&ioend->io_list); ioend->io_type = wpc->iomap.type; ioend->io_flags = wpc->iomap.flags; ioend->io_inode = inode; ioend->io_size = 0; ioend->io_offset = offset; ioend->io_bio = bio; return ioend; } /* * Allocate a new bio, and chain the old bio to the new one. * * Note that we have to do perform the chaining in this unintuitive order * so that the bi_private linkage is set up in the right direction for the * traversal in iomap_finish_ioend(). */ static struct bio * iomap_chain_bio(struct bio *prev) { struct bio *new; new = bio_alloc(GFP_NOFS, BIO_MAX_VECS); bio_copy_dev(new, prev);/* also copies over blkcg information */ new->bi_iter.bi_sector = bio_end_sector(prev); new->bi_opf = prev->bi_opf; new->bi_write_hint = prev->bi_write_hint; bio_chain(prev, new); bio_get(prev); /* for iomap_finish_ioend */ submit_bio(prev); return new; } static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t offset, sector_t sector) { if ((wpc->iomap.flags & IOMAP_F_SHARED) != (wpc->ioend->io_flags & IOMAP_F_SHARED)) return false; if (wpc->iomap.type != wpc->ioend->io_type) return false; if (offset != wpc->ioend->io_offset + wpc->ioend->io_size) return false; if (sector != bio_end_sector(wpc->ioend->io_bio)) return false; return true; } /* * Test to see if we have an existing ioend structure that we could append to * first, otherwise finish off the current ioend and start another. */ static void iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page, struct iomap_page *iop, struct iomap_writepage_ctx *wpc, struct writeback_control *wbc, struct list_head *iolist) { sector_t sector = iomap_sector(&wpc->iomap, offset); unsigned len = i_blocksize(inode); unsigned poff = offset & (PAGE_SIZE - 1); if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) { if (wpc->ioend) list_add(&wpc->ioend->io_list, iolist); wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc); } if (bio_add_page(wpc->ioend->io_bio, page, len, poff) != len) { wpc->ioend->io_bio = iomap_chain_bio(wpc->ioend->io_bio); __bio_add_page(wpc->ioend->io_bio, page, len, poff); } if (iop) atomic_add(len, &iop->write_bytes_pending); wpc->ioend->io_size += len; wbc_account_cgroup_owner(wbc, page, len); } /* * We implement an immediate ioend submission policy here to avoid needing to * chain multiple ioends and hence nest mempool allocations which can violate * forward progress guarantees we need to provide. The current ioend we are * adding blocks to is cached on the writepage context, and if the new block * does not append to the cached ioend it will create a new ioend and cache that * instead. * * If a new ioend is created and cached, the old ioend is returned and queued * locally for submission once the entire page is processed or an error has been * detected. While ioends are submitted immediately after they are completed, * batching optimisations are provided by higher level block plugging. * * At the end of a writeback pass, there will be a cached ioend remaining on the * writepage context that the caller will need to submit. */ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc, struct writeback_control *wbc, struct inode *inode, struct page *page, u64 end_offset) { struct iomap_page *iop = iomap_page_create(inode, page); struct iomap_ioend *ioend, *next; unsigned len = i_blocksize(inode); u64 file_offset; /* file offset of page */ int error = 0, count = 0, i; LIST_HEAD(submit_list); WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0); /* * Walk through the page to find areas to write back. If we run off the * end of the current map or find the current map invalid, grab a new * one. */ for (i = 0, file_offset = page_offset(page); i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; i++, file_offset += len) { if (iop && !test_bit(i, iop->uptodate)) continue; error = wpc->ops->map_blocks(wpc, inode, file_offset); if (error) break; if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE)) continue; if (wpc->iomap.type == IOMAP_HOLE) continue; iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc, &submit_list); count++; } WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list)); WARN_ON_ONCE(!PageLocked(page)); WARN_ON_ONCE(PageWriteback(page)); WARN_ON_ONCE(PageDirty(page)); /* * We cannot cancel the ioend directly here on error. We may have * already set other pages under writeback and hence we have to run I/O * completion to mark the error state of the pages under writeback * appropriately. */ if (unlikely(error)) { /* * Let the filesystem know what portion of the current page * failed to map. If the page wasn't been added to ioend, it * won't be affected by I/O completion and we must unlock it * now. */ if (wpc->ops->discard_page) wpc->ops->discard_page(page, file_offset); if (!count) { ClearPageUptodate(page); unlock_page(page); goto done; } } set_page_writeback(page); unlock_page(page); /* * Preserve the original error if there was one, otherwise catch * submission errors here and propagate into subsequent ioend * submissions. */ list_for_each_entry_safe(ioend, next, &submit_list, io_list) { int error2; list_del_init(&ioend->io_list); error2 = iomap_submit_ioend(wpc, ioend, error); if (error2 && !error) error = error2; } /* * We can end up here with no error and nothing to write only if we race * with a partial page truncate on a sub-page block sized filesystem. */ if (!count) end_page_writeback(page); done: mapping_set_error(page->mapping, error); return error; } /* * Write out a dirty page. * * For delalloc space on the page we need to allocate space and flush it. * For unwritten space on the page we need to start the conversion to * regular allocated space. */ static int iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) { struct iomap_writepage_ctx *wpc = data; struct inode *inode = page->mapping->host; pgoff_t end_index; u64 end_offset; loff_t offset; trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE); /* * Refuse to write the page out if we are called from reclaim context. * * This avoids stack overflows when called from deeply used stacks in * random callers for direct reclaim or memcg reclaim. We explicitly * allow reclaim from kswapd as the stack usage there is relatively low. * * This should never happen except in the case of a VM regression so * warn about it. */ if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)) goto redirty; /* * Is this page beyond the end of the file? * * The page index is less than the end_index, adjust the end_offset * to the highest offset that this page should represent. * ----------------------------------------------------- * | file mapping | | * ----------------------------------------------------- * | Page ... | Page N-2 | Page N-1 | Page N | | * ^--------------------------------^----------|-------- * | desired writeback range | see else | * ---------------------------------^------------------| */ offset = i_size_read(inode); end_index = offset >> PAGE_SHIFT; if (page->index < end_index) end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT; else { /* * Check whether the page to write out is beyond or straddles * i_size or not. * ------------------------------------------------------- * | file mapping | | * ------------------------------------------------------- * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | * ^--------------------------------^-----------|--------- * | | Straddles | * ---------------------------------^-----------|--------| */ unsigned offset_into_page = offset & (PAGE_SIZE - 1); /* * Skip the page if it is fully outside i_size, e.g. due to a * truncate operation that is in progress. We must redirty the * page so that reclaim stops reclaiming it. Otherwise * iomap_vm_releasepage() is called on it and gets confused. * * Note that the end_index is unsigned long, it would overflow * if the given offset is greater than 16TB on 32-bit system * and if we do check the page is fully outside i_size or not * via "if (page->index >= end_index + 1)" as "end_index + 1" * will be evaluated to 0. Hence this page will be redirtied * and be written out repeatedly which would result in an * infinite loop, the user program that perform this operation * will hang. Instead, we can verify this situation by checking * if the page to write is totally beyond the i_size or if it's * offset is just equal to the EOF. */ if (page->index > end_index || (page->index == end_index && offset_into_page == 0)) goto redirty; /* * The page straddles i_size. It must be zeroed out on each * and every writepage invocation because it may be mmapped. * "A file is mapped in multiples of the page size. For a file * that is not a multiple of the page size, the remaining * memory is zeroed when mapped, and writes to that region are * not written out to the file." */ zero_user_segment(page, offset_into_page, PAGE_SIZE); /* Adjust the end_offset to the end of file */ end_offset = offset; } return iomap_writepage_map(wpc, wbc, inode, page, end_offset); redirty: redirty_page_for_writepage(wbc, page); unlock_page(page); return 0; } int iomap_writepage(struct page *page, struct writeback_control *wbc, struct iomap_writepage_ctx *wpc, const struct iomap_writeback_ops *ops) { int ret; wpc->ops = ops; ret = iomap_do_writepage(page, wbc, wpc); if (!wpc->ioend) return ret; return iomap_submit_ioend(wpc, wpc->ioend, ret); } EXPORT_SYMBOL_GPL(iomap_writepage); int iomap_writepages(struct address_space *mapping, struct writeback_control *wbc, struct iomap_writepage_ctx *wpc, const struct iomap_writeback_ops *ops) { int ret; wpc->ops = ops; ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc); if (!wpc->ioend) return ret; return iomap_submit_ioend(wpc, wpc->ioend, ret); } EXPORT_SYMBOL_GPL(iomap_writepages); static int __init iomap_init(void) { return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), offsetof(struct iomap_ioend, io_inline_bio), BIOSET_NEED_BVECS); } fs_initcall(iomap_init);