| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright (C) 2010 Red Hat, Inc. |
| * Copyright (C) 2016-2019 Christoph Hellwig. |
| */ |
| #include <linux/module.h> |
| #include <linux/compiler.h> |
| #include <linux/fs.h> |
| #include <linux/iomap.h> |
| #include <linux/pagemap.h> |
| #include <linux/uio.h> |
| #include <linux/buffer_head.h> |
| #include <linux/dax.h> |
| #include <linux/writeback.h> |
| #include <linux/list_sort.h> |
| #include <linux/swap.h> |
| #include <linux/bio.h> |
| #include <linux/sched/signal.h> |
| #include <linux/migrate.h> |
| #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; |
| }; |
| |
| /** |
| * iomap_read_inline_data - copy inline data into the page cache |
| * @iter: iteration structure |
| * @page: page to copy to |
| * |
| * Copy the inline data in @iter into @page and zero out the rest of the page. |
| * Only a single IOMAP_INLINE extent is allowed at the end of each file. |
| * Returns zero for success to complete the read, or the usual negative errno. |
| */ |
| static int iomap_read_inline_data(const struct iomap_iter *iter, |
| struct page *page) |
| { |
| const struct iomap *iomap = iomap_iter_srcmap(iter); |
| size_t size = i_size_read(iter->inode) - iomap->offset; |
| size_t poff = offset_in_page(iomap->offset); |
| void *addr; |
| |
| if (PageUptodate(page)) |
| return 0; |
| |
| if (WARN_ON_ONCE(size > PAGE_SIZE - poff)) |
| return -EIO; |
| if (WARN_ON_ONCE(size > PAGE_SIZE - |
| offset_in_page(iomap->inline_data))) |
| return -EIO; |
| if (WARN_ON_ONCE(size > iomap->length)) |
| return -EIO; |
| if (poff > 0) |
| iomap_page_create(iter->inode, page); |
| |
| addr = kmap_local_page(page) + poff; |
| memcpy(addr, iomap->inline_data, size); |
| memset(addr + size, 0, PAGE_SIZE - poff - size); |
| kunmap_local(addr); |
| iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff); |
| return 0; |
| } |
| |
| static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter, |
| loff_t pos) |
| { |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| |
| return srcmap->type != IOMAP_MAPPED || |
| (srcmap->flags & IOMAP_F_NEW) || |
| pos >= i_size_read(iter->inode); |
| } |
| |
| static loff_t iomap_readpage_iter(const struct iomap_iter *iter, |
| struct iomap_readpage_ctx *ctx, loff_t offset) |
| { |
| const struct iomap *iomap = &iter->iomap; |
| loff_t pos = iter->pos + offset; |
| loff_t length = iomap_length(iter) - offset; |
| 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) |
| return iomap_read_inline_data(iter, page); |
| |
| /* zero post-eof blocks as the page may be mapped */ |
| iop = iomap_page_create(iter->inode, page); |
| iomap_adjust_read_range(iter->inode, iop, &pos, length, &poff, &plen); |
| if (plen == 0) |
| goto done; |
| |
| if (iomap_block_needs_zeroing(iter, 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_iter iter = { |
| .inode = page->mapping->host, |
| .pos = page_offset(page), |
| .len = PAGE_SIZE, |
| }; |
| struct iomap_readpage_ctx ctx = { |
| .cur_page = page, |
| }; |
| int ret; |
| |
| trace_iomap_readpage(page->mapping->host, 1); |
| |
| while ((ret = iomap_iter(&iter, ops)) > 0) |
| iter.processed = iomap_readpage_iter(&iter, &ctx, 0); |
| |
| if (ret < 0) |
| SetPageError(page); |
| |
| 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 throughout the stack eventually. |
| */ |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(iomap_readpage); |
| |
| static loff_t iomap_readahead_iter(const struct iomap_iter *iter, |
| struct iomap_readpage_ctx *ctx) |
| { |
| loff_t length = iomap_length(iter); |
| loff_t done, ret; |
| |
| for (done = 0; done < length; done += ret) { |
| if (ctx->cur_page && offset_in_page(iter->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_iter(iter, ctx, done); |
| if (ret <= 0) |
| return ret; |
| } |
| |
| 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 iomap_iter iter = { |
| .inode = rac->mapping->host, |
| .pos = readahead_pos(rac), |
| .len = readahead_length(rac), |
| }; |
| struct iomap_readpage_ctx ctx = { |
| .rac = rac, |
| }; |
| |
| trace_iomap_readahead(rac->mapping->host, readahead_count(rac)); |
| |
| while (iomap_iter(&iter, ops) > 0) |
| iter.processed = iomap_readahead_iter(&iter, &ctx); |
| |
| 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're 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 */ |
| |
| 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, const 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(const struct iomap_iter *iter, loff_t pos, |
| unsigned len, struct page *page) |
| { |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| struct iomap_page *iop = iomap_page_create(iter->inode, page); |
| loff_t block_size = i_blocksize(iter->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(iter->inode, iop, &block_start, |
| block_end - block_start, &poff, &plen); |
| if (plen == 0) |
| break; |
| |
| if (!(iter->flags & IOMAP_UNSHARE) && |
| (from <= poff || from >= poff + plen) && |
| (to <= poff || to >= poff + plen)) |
| continue; |
| |
| if (iomap_block_needs_zeroing(iter, block_start)) { |
| if (WARN_ON_ONCE(iter->flags & IOMAP_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_inline(const struct iomap_iter *iter, |
| struct page *page) |
| { |
| /* needs more work for the tailpacking case; disable for now */ |
| if (WARN_ON_ONCE(iomap_iter_srcmap(iter)->offset != 0)) |
| return -EIO; |
| return iomap_read_inline_data(iter, page); |
| } |
| |
| static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, |
| unsigned len, struct page **pagep) |
| { |
| const struct iomap_page_ops *page_ops = iter->iomap.page_ops; |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| struct page *page; |
| int status = 0; |
| |
| BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length); |
| if (srcmap != &iter->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(iter->inode, pos, len); |
| if (status) |
| return status; |
| } |
| |
| page = grab_cache_page_write_begin(iter->inode->i_mapping, |
| pos >> PAGE_SHIFT, AOP_FLAG_NOFS); |
| if (!page) { |
| status = -ENOMEM; |
| goto out_no_page; |
| } |
| |
| if (srcmap->type == IOMAP_INLINE) |
| status = iomap_write_begin_inline(iter, page); |
| else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) |
| status = __block_write_begin_int(page, pos, len, NULL, srcmap); |
| else |
| status = __iomap_write_begin(iter, pos, len, page); |
| |
| if (unlikely(status)) |
| goto out_unlock; |
| |
| *pagep = page; |
| return 0; |
| |
| out_unlock: |
| unlock_page(page); |
| put_page(page); |
| iomap_write_failed(iter->inode, pos, len); |
| |
| out_no_page: |
| if (page_ops && page_ops->page_done) |
| page_ops->page_done(iter->inode, pos, 0, NULL); |
| 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've 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(const struct iomap_iter *iter, |
| struct page *page, loff_t pos, size_t copied) |
| { |
| const struct iomap *iomap = &iter->iomap; |
| void *addr; |
| |
| WARN_ON_ONCE(!PageUptodate(page)); |
| BUG_ON(!iomap_inline_data_valid(iomap)); |
| |
| flush_dcache_page(page); |
| addr = kmap_local_page(page) + pos; |
| memcpy(iomap_inline_data(iomap, pos), addr, copied); |
| kunmap_local(addr); |
| |
| mark_inode_dirty(iter->inode); |
| return copied; |
| } |
| |
| /* Returns the number of bytes copied. May be 0. Cannot be an errno. */ |
| static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len, |
| size_t copied, struct page *page) |
| { |
| const struct iomap_page_ops *page_ops = iter->iomap.page_ops; |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| loff_t old_size = iter->inode->i_size; |
| size_t ret; |
| |
| if (srcmap->type == IOMAP_INLINE) { |
| ret = iomap_write_end_inline(iter, page, pos, copied); |
| } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) { |
| ret = block_write_end(NULL, iter->inode->i_mapping, pos, len, |
| copied, page, NULL); |
| } else { |
| ret = __iomap_write_end(iter->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(iter->inode, pos + ret); |
| iter->iomap.flags |= IOMAP_F_SIZE_CHANGED; |
| } |
| unlock_page(page); |
| |
| if (old_size < pos) |
| pagecache_isize_extended(iter->inode, old_size, pos); |
| if (page_ops && page_ops->page_done) |
| page_ops->page_done(iter->inode, pos, ret, page); |
| put_page(page); |
| |
| if (ret < len) |
| iomap_write_failed(iter->inode, pos, len); |
| return ret; |
| } |
| |
| static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) |
| { |
| loff_t length = iomap_length(iter); |
| loff_t pos = iter->pos; |
| ssize_t written = 0; |
| long status = 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'll 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(fault_in_iov_iter_readable(i, bytes))) { |
| status = -EFAULT; |
| break; |
| } |
| |
| status = iomap_write_begin(iter, pos, bytes, &page); |
| if (unlikely(status)) |
| break; |
| |
| if (mapping_writably_mapped(iter->inode->i_mapping)) |
| flush_dcache_page(page); |
| |
| copied = copy_page_from_iter_atomic(page, offset, bytes, i); |
| |
| status = iomap_write_end(iter, pos, bytes, copied, page); |
| |
| 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(iter->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 *i, |
| const struct iomap_ops *ops) |
| { |
| struct iomap_iter iter = { |
| .inode = iocb->ki_filp->f_mapping->host, |
| .pos = iocb->ki_pos, |
| .len = iov_iter_count(i), |
| .flags = IOMAP_WRITE, |
| }; |
| int ret; |
| |
| while ((ret = iomap_iter(&iter, ops)) > 0) |
| iter.processed = iomap_write_iter(&iter, i); |
| if (iter.pos == iocb->ki_pos) |
| return ret; |
| return iter.pos - iocb->ki_pos; |
| } |
| EXPORT_SYMBOL_GPL(iomap_file_buffered_write); |
| |
| static loff_t iomap_unshare_iter(struct iomap_iter *iter) |
| { |
| struct iomap *iomap = &iter->iomap; |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| loff_t pos = iter->pos; |
| loff_t length = iomap_length(iter); |
| 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(iter, pos, bytes, &page); |
| if (unlikely(status)) |
| return status; |
| |
| status = iomap_write_end(iter, pos, bytes, bytes, page); |
| if (WARN_ON_ONCE(status == 0)) |
| return -EIO; |
| |
| cond_resched(); |
| |
| pos += status; |
| written += status; |
| length -= status; |
| |
| balance_dirty_pages_ratelimited(iter->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) |
| { |
| struct iomap_iter iter = { |
| .inode = inode, |
| .pos = pos, |
| .len = len, |
| .flags = IOMAP_WRITE | IOMAP_UNSHARE, |
| }; |
| int ret; |
| |
| while ((ret = iomap_iter(&iter, ops)) > 0) |
| iter.processed = iomap_unshare_iter(&iter); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(iomap_file_unshare); |
| |
| static s64 __iomap_zero_iter(struct iomap_iter *iter, loff_t pos, u64 length) |
| { |
| struct page *page; |
| int status; |
| unsigned offset = offset_in_page(pos); |
| unsigned bytes = min_t(u64, PAGE_SIZE - offset, length); |
| |
| status = iomap_write_begin(iter, pos, bytes, &page); |
| if (status) |
| return status; |
| |
| zero_user(page, offset, bytes); |
| mark_page_accessed(page); |
| |
| return iomap_write_end(iter, pos, bytes, bytes, page); |
| } |
| |
| static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero) |
| { |
| struct iomap *iomap = &iter->iomap; |
| const struct iomap *srcmap = iomap_iter_srcmap(iter); |
| loff_t pos = iter->pos; |
| loff_t length = iomap_length(iter); |
| 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(iter->inode)) |
| bytes = dax_iomap_zero(pos, length, iomap); |
| else |
| bytes = __iomap_zero_iter(iter, pos, length); |
| 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) |
| { |
| struct iomap_iter iter = { |
| .inode = inode, |
| .pos = pos, |
| .len = len, |
| .flags = IOMAP_ZERO, |
| }; |
| int ret; |
| |
| while ((ret = iomap_iter(&iter, ops)) > 0) |
| iter.processed = iomap_zero_iter(&iter, did_zero); |
| return ret; |
| } |
| 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_iter(struct iomap_iter *iter, |
| struct page *page) |
| { |
| loff_t length = iomap_length(iter); |
| int ret; |
| |
| if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) { |
| ret = __block_write_begin_int(page, iter->pos, length, NULL, |
| &iter->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 iomap_iter iter = { |
| .inode = file_inode(vmf->vma->vm_file), |
| .flags = IOMAP_WRITE | IOMAP_FAULT, |
| }; |
| struct page *page = vmf->page; |
| ssize_t ret; |
| |
| lock_page(page); |
| ret = page_mkwrite_check_truncate(page, iter.inode); |
| if (ret < 0) |
| goto out_unlock; |
| iter.pos = page_offset(page); |
| iter.len = ret; |
| while ((ret = iomap_iter(&iter, ops)) > 0) |
| iter.processed = iomap_page_mkwrite_iter(&iter, page); |
| |
| if (ret < 0) |
| goto out_unlock; |
| 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, error); |
| } |
| |
| 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've marked pages 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're 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 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 |
| * the forward progress guarantees we need to provide. The current ioend we're |
| * adding blocks to is cached in the writepage context, and if the new block |
| * doesn't 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 hasn'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; 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're 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 | <EOF> | |
| * ----------------------------------------------------- |
| * | 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 | <EOF> | |
| * ------------------------------------------------------- |
| * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | |
| * ^--------------------------------^-----------|--------- |
| * | | Straddles | |
| * ---------------------------------^-----------|--------| |
| */ |
| unsigned offset_into_page = offset & (PAGE_SIZE - 1); |
| |
| /* |
| * Skip the page if it's fully outside i_size, e.g. due to a |
| * truncate operation that's 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. If the given |
| * offset is greater than 16TB on a 32-bit system then if we |
| * checked if the page is fully outside i_size with |
| * "if (page->index >= end_index + 1)", "end_index + 1" would |
| * overflow and evaluate to 0. Hence this page would be |
| * redirtied and written out repeatedly, which would result in |
| * an infinite loop; the user program performing this operation |
| * would hang. Instead, we can detect this situation by |
| * checking if the page is totally beyond i_size or if its |
| * 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); |