diff options
Diffstat (limited to 'fs/iomap/buffered-io.c')
| -rw-r--r-- | fs/iomap/buffered-io.c | 2102 |
1 files changed, 2102 insertions, 0 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c new file mode 100644 index 000000000..0a5ebfda9 --- /dev/null +++ b/fs/iomap/buffered-io.c @@ -0,0 +1,2102 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2010 Red Hat, Inc. + * Copyright (C) 2016-2023 Christoph Hellwig. + */ +#include <linux/iomap.h> +#include <linux/buffer_head.h> +#include <linux/writeback.h> +#include <linux/swap.h> +#include <linux/migrate.h> +#include <linux/fserror.h> +#include <linux/fsverity.h> +#include "internal.h" +#include "trace.h" + +#include "../internal.h" + +/* + * Structure allocated for each folio to track per-block uptodate, dirty state + * and I/O completions. + */ +struct iomap_folio_state { + spinlock_t state_lock; + unsigned int read_bytes_pending; + atomic_t write_bytes_pending; + + /* + * Each block has two bits in this bitmap: + * Bits [0..blocks_per_folio) has the uptodate status. + * Bits [b_p_f...(2*b_p_f)) has the dirty status. + */ + unsigned long state[]; +}; + +static inline bool ifs_is_fully_uptodate(struct folio *folio, + struct iomap_folio_state *ifs) +{ + struct inode *inode = folio->mapping->host; + + return bitmap_full(ifs->state, i_blocks_per_folio(inode, folio)); +} + +/* + * Find the next uptodate block in the folio. end_blk is inclusive. + * If no uptodate block is found, this will return end_blk + 1. + */ +static unsigned ifs_next_uptodate_block(struct folio *folio, + unsigned start_blk, unsigned end_blk) +{ + struct iomap_folio_state *ifs = folio->private; + + return find_next_bit(ifs->state, end_blk + 1, start_blk); +} + +/* + * Find the next non-uptodate block in the folio. end_blk is inclusive. + * If no non-uptodate block is found, this will return end_blk + 1. + */ +static unsigned ifs_next_nonuptodate_block(struct folio *folio, + unsigned start_blk, unsigned end_blk) +{ + struct iomap_folio_state *ifs = folio->private; + + return find_next_zero_bit(ifs->state, end_blk + 1, start_blk); +} + +static bool ifs_set_range_uptodate(struct folio *folio, + struct iomap_folio_state *ifs, size_t off, size_t len) +{ + struct inode *inode = folio->mapping->host; + unsigned int first_blk, last_blk; + + if (len) { + first_blk = off >> inode->i_blkbits; + last_blk = (off + len - 1) >> inode->i_blkbits; + bitmap_set(ifs->state, first_blk, last_blk - first_blk + 1); + } + return ifs_is_fully_uptodate(folio, ifs); +} + +static void iomap_set_range_uptodate(struct folio *folio, size_t off, + size_t len) +{ + struct iomap_folio_state *ifs = folio->private; + unsigned long flags; + bool mark_uptodate = true; + + if (folio_test_uptodate(folio)) + return; + + if (ifs) { + spin_lock_irqsave(&ifs->state_lock, flags); + /* + * If a read with bytes pending is in progress, we must not call + * folio_mark_uptodate(). The read completion path + * (iomap_read_end()) will call folio_end_read(), which uses XOR + * semantics to set the uptodate bit. If we set it here, the XOR + * in folio_end_read() will clear it, leaving the folio not + * uptodate. + */ + mark_uptodate = ifs_set_range_uptodate(folio, ifs, off, len) && + !ifs->read_bytes_pending; + spin_unlock_irqrestore(&ifs->state_lock, flags); + } + + if (mark_uptodate) + folio_mark_uptodate(folio); +} + +void iomap_folio_mark_uptodate(struct folio *folio) +{ + iomap_set_range_uptodate(folio, 0, folio_size(folio)); +} +EXPORT_SYMBOL_GPL(iomap_folio_mark_uptodate); + +/* + * Find the next dirty block in the folio. end_blk is inclusive. + * If no dirty block is found, this will return end_blk + 1. + */ +static unsigned ifs_next_dirty_block(struct folio *folio, + unsigned start_blk, unsigned end_blk) +{ + struct iomap_folio_state *ifs = folio->private; + struct inode *inode = folio->mapping->host; + unsigned int blks = i_blocks_per_folio(inode, folio); + + return find_next_bit(ifs->state, blks + end_blk + 1, + blks + start_blk) - blks; +} + +/* + * Find the next clean block in the folio. end_blk is inclusive. + * If no clean block is found, this will return end_blk + 1. + */ +static unsigned ifs_next_clean_block(struct folio *folio, + unsigned start_blk, unsigned end_blk) +{ + struct iomap_folio_state *ifs = folio->private; + struct inode *inode = folio->mapping->host; + unsigned int blks = i_blocks_per_folio(inode, folio); + + return find_next_zero_bit(ifs->state, blks + end_blk + 1, + blks + start_blk) - blks; +} + +static unsigned ifs_find_dirty_range(struct folio *folio, + struct iomap_folio_state *ifs, u64 *range_start, u64 range_end) +{ + struct inode *inode = folio->mapping->host; + unsigned start_blk = + offset_in_folio(folio, *range_start) >> inode->i_blkbits; + unsigned end_blk = min_not_zero( + offset_in_folio(folio, range_end) >> inode->i_blkbits, + i_blocks_per_folio(inode, folio)) - 1; + unsigned nblks; + + start_blk = ifs_next_dirty_block(folio, start_blk, end_blk); + if (start_blk > end_blk) + return 0; + if (start_blk == end_blk) + nblks = 1; + else + nblks = ifs_next_clean_block(folio, start_blk + 1, end_blk) - + start_blk; + + *range_start = folio_pos(folio) + (start_blk << inode->i_blkbits); + return nblks << inode->i_blkbits; +} + +static unsigned iomap_find_dirty_range(struct folio *folio, u64 *range_start, + u64 range_end) +{ + struct iomap_folio_state *ifs = folio->private; + + if (*range_start >= range_end) + return 0; + + if (ifs) + return ifs_find_dirty_range(folio, ifs, range_start, range_end); + return range_end - *range_start; +} + +/* + * Clear the per-block dirty bits for the range [@off, @off + @len) within a + * folio. The range is rounded inwards so that only blocks fully covered by + * the range are cleared. This is required for operations like folio + * invalidation, where we must ensure a block is fully clean before discarding + * it. + */ +static void ifs_clear_range_dirty(struct folio *folio, + struct iomap_folio_state *ifs, size_t off, size_t len) +{ + struct inode *inode = folio->mapping->host; + unsigned int blks_per_folio = i_blocks_per_folio(inode, folio); + unsigned int first_blk = round_up(off, i_blocksize(inode)) >> + inode->i_blkbits; + unsigned int last_blk = (off + len) >> inode->i_blkbits; + unsigned long flags; + + if (first_blk >= last_blk) + return; + + spin_lock_irqsave(&ifs->state_lock, flags); + bitmap_clear(ifs->state, first_blk + blks_per_folio, + last_blk - first_blk); + spin_unlock_irqrestore(&ifs->state_lock, flags); +} + +static void iomap_clear_range_dirty(struct folio *folio, size_t off, size_t len) +{ + struct iomap_folio_state *ifs = folio->private; + + if (ifs) + ifs_clear_range_dirty(folio, ifs, off, len); +} + +/* + * Set the per-block dirty bits for the range [@off, @off + @len) within a + * folio. The range is rounded outwards so that any block partially touched + * by the range is marked dirty. This ensures blocks containing even a + * single dirty byte will be included in subsequent writeback, preventing + * data loss when partial blocks are written. + */ +static void ifs_set_range_dirty(struct folio *folio, + struct iomap_folio_state *ifs, size_t off, size_t len) +{ + struct inode *inode = folio->mapping->host; + unsigned int blks_per_folio = i_blocks_per_folio(inode, folio); + unsigned int first_blk, last_blk; + unsigned long flags; + + if (!len) + return; + + first_blk = off >> inode->i_blkbits; + last_blk = (off + len - 1) >> inode->i_blkbits; + spin_lock_irqsave(&ifs->state_lock, flags); + bitmap_set(ifs->state, first_blk + blks_per_folio, + last_blk - first_blk + 1); + spin_unlock_irqrestore(&ifs->state_lock, flags); +} + +static void iomap_set_range_dirty(struct folio *folio, size_t off, size_t len) +{ + struct iomap_folio_state *ifs = folio->private; + + if (ifs) + ifs_set_range_dirty(folio, ifs, off, len); +} + +static struct iomap_folio_state *ifs_alloc(struct inode *inode, + struct folio *folio, unsigned int flags) +{ + struct iomap_folio_state *ifs = folio->private; + unsigned int nr_blocks = i_blocks_per_folio(inode, folio); + gfp_t gfp; + + if (ifs || nr_blocks <= 1) + return ifs; + + if (flags & IOMAP_NOWAIT) + gfp = GFP_NOWAIT; + else + gfp = GFP_NOFS | __GFP_NOFAIL; + + /* + * ifs->state tracks two sets of state flags when the + * filesystem block size is smaller than the folio size. + * The first state tracks per-block uptodate and the + * second tracks per-block dirty state. + */ + ifs = kzalloc_flex(*ifs, state, BITS_TO_LONGS(2 * nr_blocks), gfp); + if (!ifs) + return ifs; + + spin_lock_init(&ifs->state_lock); + if (folio_test_uptodate(folio)) + bitmap_set(ifs->state, 0, nr_blocks); + if (folio_test_dirty(folio)) + bitmap_set(ifs->state, nr_blocks, nr_blocks); + folio_attach_private(folio, ifs); + + return ifs; +} + +static void ifs_free(struct folio *folio) +{ + struct iomap_folio_state *ifs = folio_detach_private(folio); + + if (!ifs) + return; + WARN_ON_ONCE(ifs->read_bytes_pending != 0); + WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending)); + WARN_ON_ONCE(ifs_is_fully_uptodate(folio, ifs) != + folio_test_uptodate(folio)); + kfree(ifs); +} + +/* + * Calculate how many bytes to truncate based off the number of blocks to + * truncate and the end position to start truncating from. + */ +static size_t iomap_bytes_to_truncate(loff_t end_pos, unsigned block_bits, + unsigned blocks_truncated) +{ + unsigned block_size = 1 << block_bits; + unsigned block_offset = end_pos & (block_size - 1); + + if (!block_offset) + return blocks_truncated << block_bits; + + return ((blocks_truncated - 1) << block_bits) + block_offset; +} + +/* + * Calculate the range inside the folio that we actually need to read. + */ +static void iomap_adjust_read_range(struct inode *inode, struct folio *folio, + loff_t *pos, loff_t length, size_t *offp, size_t *lenp) +{ + struct iomap_folio_state *ifs = folio->private; + loff_t orig_pos = *pos; + loff_t isize = i_size_read(inode); + unsigned block_bits = inode->i_blkbits; + unsigned block_size = (1 << block_bits); + size_t poff = offset_in_folio(folio, *pos); + size_t plen = min_t(loff_t, folio_size(folio) - poff, length); + size_t orig_plen = plen; + 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 (ifs) { + unsigned int next, blocks_skipped; + + next = ifs_next_nonuptodate_block(folio, first, last); + blocks_skipped = next - first; + + if (blocks_skipped) { + unsigned long block_offset = *pos & (block_size - 1); + unsigned bytes_skipped = + (blocks_skipped << block_bits) - block_offset; + + *pos += bytes_skipped; + poff += bytes_skipped; + plen -= bytes_skipped; + } + first = next; + + /* truncate len if we find any trailing uptodate block(s) */ + if (++next <= last) { + next = ifs_next_uptodate_block(folio, next, last); + if (next <= last) { + plen -= iomap_bytes_to_truncate(*pos + plen, + block_bits, last - next + 1); + last = next - 1; + } + } + } + + /* + * 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 + orig_plen > isize) { + unsigned end = offset_in_folio(folio, isize - 1) >> block_bits; + + if (first <= end && last > end) + plen -= iomap_bytes_to_truncate(*pos + plen, block_bits, + last - end); + } + + *offp = poff; + *lenp = plen; +} + +static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter, + loff_t pos) +{ + const struct iomap *srcmap = iomap_iter_srcmap(iter); + + /* + * If this block has not been written, there's nothing to read + */ + if (srcmap->type != IOMAP_MAPPED) + return true; + + /* + * Newly allocated blocks have not been written + */ + if (srcmap->flags & IOMAP_F_NEW) + return true; + + /* + * fsverity metadata is stored past i_size, we need to read it instead + * of zeroing + */ + if (srcmap->flags & IOMAP_F_FSVERITY) + return false; + + return pos >= i_size_read(iter->inode); +} + +/** + * iomap_read_inline_data - copy inline data into the page cache + * @iter: iteration structure + * @folio: folio to copy to + * + * Copy the inline data in @iter into @folio and zero out the rest of the folio. + * 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 folio *folio) +{ + const struct iomap *iomap = iomap_iter_srcmap(iter); + size_t size = i_size_read(iter->inode) - iomap->offset; + size_t offset = offset_in_folio(folio, iomap->offset); + + if (WARN_ON_ONCE(!iomap->inline_data)) + return -EIO; + + if (folio_test_uptodate(folio)) + return 0; + + if (WARN_ON_ONCE(size > iomap->length)) { + fserror_report_io(iter->inode, FSERR_BUFFERED_READ, + iomap->offset, size, -EIO, GFP_NOFS); + return -EIO; + } + if (offset > 0) + ifs_alloc(iter->inode, folio, iter->flags); + + folio_fill_tail(folio, offset, iomap->inline_data, size); + iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset); + return 0; +} + +void iomap_finish_folio_read(struct folio *folio, size_t off, size_t len, + int error) +{ + struct iomap_folio_state *ifs = folio->private; + bool uptodate = !error; + bool finished = true; + + if (error) + fserror_report_io(folio->mapping->host, FSERR_BUFFERED_READ, + folio_pos(folio) + off, len, error, + GFP_ATOMIC); + + if (ifs) { + unsigned long flags; + + spin_lock_irqsave(&ifs->state_lock, flags); + if (!error) + uptodate = ifs_set_range_uptodate(folio, ifs, off, len); + ifs->read_bytes_pending -= len; + finished = !ifs->read_bytes_pending; + spin_unlock_irqrestore(&ifs->state_lock, flags); + } + + if (finished) + folio_end_read(folio, uptodate); +} +EXPORT_SYMBOL_GPL(iomap_finish_folio_read); + +static void iomap_read_init(struct folio *folio) +{ + struct iomap_folio_state *ifs = folio->private; + + if (ifs) { + /* + * ifs->read_bytes_pending is used to track how many bytes are + * read in asynchronously by the IO helper. We need to track + * this so that we can know when the IO helper has finished + * reading in all the necessary ranges of the folio and can end + * the read. + * + * Increase ->read_bytes_pending by the folio size to start. + * We'll subtract any uptodate / zeroed ranges that did not + * require IO in iomap_read_end() after we're done processing + * the folio. + * + * We do this because otherwise, we would have to increment + * ifs->read_bytes_pending every time a range in the folio needs + * to be read in, which can get expensive since the spinlock + * needs to be held whenever modifying ifs->read_bytes_pending. + */ + spin_lock_irq(&ifs->state_lock); + WARN_ON_ONCE(ifs->read_bytes_pending != 0); + ifs->read_bytes_pending = folio_size(folio); + spin_unlock_irq(&ifs->state_lock); + } +} + +/* + * This ends IO if no bytes were submitted to an IO helper. + * + * Otherwise, this calibrates ifs->read_bytes_pending to represent only the + * submitted bytes (see comment in iomap_read_init()). If all bytes submitted + * have already been completed by the IO helper, then this will end the read. + * Else the IO helper will end the read after all submitted ranges have been + * read. + */ +static void iomap_read_end(struct folio *folio, size_t bytes_submitted) +{ + struct iomap_folio_state *ifs = folio->private; + + if (ifs) { + bool end_read, uptodate; + + spin_lock_irq(&ifs->state_lock); + if (!ifs->read_bytes_pending) { + WARN_ON_ONCE(bytes_submitted); + spin_unlock_irq(&ifs->state_lock); + folio_unlock(folio); + return; + } + + /* + * Subtract any bytes that were initially accounted to + * read_bytes_pending but skipped for IO. + */ + ifs->read_bytes_pending -= folio_size(folio) - bytes_submitted; + + /* + * If !ifs->read_bytes_pending, this means all pending reads by + * the IO helper have already completed, which means we need to + * end the folio read here. If ifs->read_bytes_pending != 0, + * the IO helper will end the folio read. + */ + end_read = !ifs->read_bytes_pending; + if (end_read) + uptodate = ifs_is_fully_uptodate(folio, ifs); + spin_unlock_irq(&ifs->state_lock); + if (end_read) + folio_end_read(folio, uptodate); + } else { + /* + * If a folio without an ifs is submitted to the IO helper, the + * read must be on the entire folio and the IO helper takes + * ownership of the folio. This means we should only enter + * iomap_read_end() for the !ifs case if no bytes were submitted + * to the IO helper, in which case we are responsible for + * unlocking the folio here. + */ + WARN_ON_ONCE(bytes_submitted); + folio_unlock(folio); + } +} + +static int iomap_read_folio_iter(struct iomap_iter *iter, + struct iomap_read_folio_ctx *ctx, size_t *bytes_submitted) +{ + const struct iomap *iomap = &iter->iomap; + loff_t pos = iter->pos; + loff_t length = iomap_length(iter); + struct folio *folio = ctx->cur_folio; + size_t folio_len = folio_size(folio); + struct iomap_folio_state *ifs; + size_t poff, plen; + loff_t pos_diff; + int ret; + + if (iomap->type == IOMAP_INLINE) { + ret = iomap_read_inline_data(iter, folio); + if (ret) + return ret; + return iomap_iter_advance(iter, length); + } + + ifs = ifs_alloc(iter->inode, folio, iter->flags); + + length = min_t(loff_t, length, folio_len - offset_in_folio(folio, pos)); + while (length) { + iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, + &plen); + + pos_diff = pos - iter->pos; + if (WARN_ON_ONCE(pos_diff + plen > length)) + return -EIO; + + ret = iomap_iter_advance(iter, pos_diff); + if (ret) + return ret; + + if (plen == 0) + return 0; + + /* + * Handling of fsverity "holes". We hit this for two case: + * 1. No need to go further, the hole after fsverity + * descriptor is the end of the fsverity metadata. + * + * 2. This folio contains merkle tree blocks which need to be + * synthesized. If we already have fsverity info (ctx->vi) + * synthesize these blocks. + */ + if ((iomap->flags & IOMAP_F_FSVERITY) && + iomap->type == IOMAP_HOLE) { + if (ctx->vi) + fsverity_fill_zerohash(folio, poff, plen, + ctx->vi); + iomap_set_range_uptodate(folio, poff, plen); + } else if (iomap_block_needs_zeroing(iter, pos)) { + /* zero post-eof blocks as the page may be mapped */ + folio_zero_range(folio, poff, plen); + if (ctx->vi && + !fsverity_verify_blocks(ctx->vi, folio, plen, poff)) + return -EIO; + iomap_set_range_uptodate(folio, poff, plen); + } else { + if (!*bytes_submitted) + iomap_read_init(folio); + ret = ctx->ops->read_folio_range(iter, ctx, plen); + if (ret < 0) + fserror_report_io(iter->inode, + FSERR_BUFFERED_READ, pos, + plen, ret, GFP_NOFS); + if (ret) + return ret; + + *bytes_submitted += plen; + /* + * Hand off folio ownership to the IO helper when: + * 1) The entire folio has been submitted for IO, or + * 2) There is no ifs attached to the folio + * + * Case (2) occurs when 1 << i_blkbits matches the folio + * size but the underlying filesystem or block device + * uses a smaller granularity for IO. + */ + if (*bytes_submitted == folio_len || !ifs) + ctx->cur_folio = NULL; + } + + ret = iomap_iter_advance(iter, plen); + if (ret) + return ret; + length -= pos_diff + plen; + pos = iter->pos; + } + return 0; +} + +void iomap_read_folio(const struct iomap_ops *ops, + struct iomap_read_folio_ctx *ctx, void *private) +{ + struct folio *folio = ctx->cur_folio; + struct iomap_iter iter = { + .inode = folio->mapping->host, + .pos = folio_pos(folio), + .len = folio_size(folio), + .private = private, + }; + size_t bytes_submitted = 0; + int ret; + + trace_iomap_readpage(iter.inode, 1); + + /* + * Fetch fsverity_info for both data and fsverity metadata, as iomap + * needs zeroed hash for merkle tree block synthesis + */ + ctx->vi = fsverity_get_info(iter.inode); + if (ctx->vi && iter.pos < i_size_read(iter.inode)) + fsverity_readahead(ctx->vi, folio->index, + folio_nr_pages(folio)); + + while ((ret = iomap_iter(&iter, ops)) > 0) { + iter.status = iomap_read_folio_iter(&iter, ctx, + &bytes_submitted); + if (ctx->read_ctx && ctx->ops->submit_read) + ctx->ops->submit_read(&iter, ctx); + } + + if (ctx->cur_folio) + iomap_read_end(ctx->cur_folio, bytes_submitted); +} +EXPORT_SYMBOL_GPL(iomap_read_folio); + +static int iomap_readahead_iter(struct iomap_iter *iter, + struct iomap_read_folio_ctx *ctx, size_t *cur_bytes_submitted) +{ + int ret; + + while (iomap_length(iter)) { + if (ctx->cur_folio && + offset_in_folio(ctx->cur_folio, iter->pos) == 0) { + iomap_read_end(ctx->cur_folio, *cur_bytes_submitted); + ctx->cur_folio = NULL; + } + if (!ctx->cur_folio) { + ctx->cur_folio = readahead_folio(ctx->rac); + if (WARN_ON_ONCE(!ctx->cur_folio)) + return -EINVAL; + *cur_bytes_submitted = 0; + } + ret = iomap_read_folio_iter(iter, ctx, cur_bytes_submitted); + if (ret) + return ret; + } + + return 0; +} + +/** + * iomap_readahead - Attempt to read pages from a file. + * @ops: The operations vector for the filesystem. + * @ctx: The ctx used for issuing readahead. + * @private: The filesystem-specific information for issuing iomap_iter. + * + * 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(const struct iomap_ops *ops, + struct iomap_read_folio_ctx *ctx, void *private) +{ + struct readahead_control *rac = ctx->rac; + struct iomap_iter iter = { + .inode = rac->mapping->host, + .pos = readahead_pos(rac), + .len = readahead_length(rac), + .private = private, + }; + size_t cur_bytes_submitted; + + trace_iomap_readahead(rac->mapping->host, readahead_count(rac)); + + /* + * Fetch fsverity_info for both data and fsverity metadata, as iomap + * needs zeroed hash for merkle tree block synthesis + */ + ctx->vi = fsverity_get_info(iter.inode); + if (ctx->vi && iter.pos < i_size_read(iter.inode)) + fsverity_readahead(ctx->vi, readahead_index(rac), + readahead_count(rac)); + + while (iomap_iter(&iter, ops) > 0) { + iter.status = iomap_readahead_iter(&iter, ctx, + &cur_bytes_submitted); + if (ctx->read_ctx && ctx->ops->submit_read) + ctx->ops->submit_read(&iter, ctx); + } + + if (ctx->cur_folio) + iomap_read_end(ctx->cur_folio, cur_bytes_submitted); +} +EXPORT_SYMBOL_GPL(iomap_readahead); + +/* + * iomap_is_partially_uptodate checks whether blocks within a folio are + * uptodate or not. + * + * Returns true if all blocks which correspond to the specified part + * of the folio are uptodate. + */ +bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count) +{ + struct iomap_folio_state *ifs = folio->private; + struct inode *inode = folio->mapping->host; + unsigned first, last; + + if (!ifs) + return false; + + /* Caller's range may extend past the end of this folio */ + count = min(folio_size(folio) - from, count); + + /* First and last blocks in range within folio */ + first = from >> inode->i_blkbits; + last = (from + count - 1) >> inode->i_blkbits; + + return ifs_next_nonuptodate_block(folio, first, last) > last; +} +EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate); + +/** + * iomap_get_folio - get a folio reference for writing + * @iter: iteration structure + * @pos: start offset of write + * @len: Suggested size of folio to create. + * + * Returns a locked reference to the folio at @pos, or an error pointer if the + * folio could not be obtained. + */ +struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len) +{ + fgf_t fgp = FGP_WRITEBEGIN; + + if (iter->flags & IOMAP_NOWAIT) + fgp |= FGP_NOWAIT; + if (iter->flags & IOMAP_DONTCACHE) + fgp |= FGP_DONTCACHE; + fgp |= fgf_set_order(len); + + return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT, + fgp, mapping_gfp_mask(iter->inode->i_mapping)); +} +EXPORT_SYMBOL_GPL(iomap_get_folio); + +bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags) +{ + trace_iomap_release_folio(folio->mapping->host, folio_pos(folio), + folio_size(folio)); + + /* + * If the folio is dirty, we refuse to release our metadata because + * it may be partially dirty. Once we track per-block dirty state, + * we can release the metadata if every block is dirty. + */ + if (folio_test_dirty(folio)) + return false; + ifs_free(folio); + return true; +} +EXPORT_SYMBOL_GPL(iomap_release_folio); + +void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len) +{ + trace_iomap_invalidate_folio(folio->mapping->host, + folio_pos(folio) + offset, len); + + /* + * If we're invalidating the entire folio, clear the dirty state + * from it and release it to avoid unnecessary buildup of the LRU. + */ + if (offset == 0 && len == folio_size(folio)) { + WARN_ON_ONCE(folio_test_writeback(folio)); + folio_cancel_dirty(folio); + ifs_free(folio); + } else { + iomap_clear_range_dirty(folio, offset, len); + } +} +EXPORT_SYMBOL_GPL(iomap_invalidate_folio); + +bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio) +{ + struct inode *inode = mapping->host; + size_t len = folio_size(folio); + + ifs_alloc(inode, folio, 0); + iomap_set_range_dirty(folio, 0, len); + return filemap_dirty_folio(mapping, folio); +} +EXPORT_SYMBOL_GPL(iomap_dirty_folio); + +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 - 1); +} + +static int __iomap_write_begin(const struct iomap_iter *iter, + const struct iomap_write_ops *write_ops, size_t len, + struct folio *folio) +{ + struct iomap_folio_state *ifs; + loff_t pos = iter->pos; + 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 int nr_blocks = i_blocks_per_folio(iter->inode, folio); + size_t from = offset_in_folio(folio, pos), to = from + len; + size_t poff, plen; + + /* + * If the write or zeroing completely overlaps the current folio, then + * entire folio will be dirtied so there is no need for + * per-block state tracking structures to be attached to this folio. + * For the unshare case, we must read in the ondisk contents because we + * are not changing pagecache contents. + */ + if (!(iter->flags & IOMAP_UNSHARE) && pos <= folio_pos(folio) && + pos + len >= folio_next_pos(folio)) + return 0; + + ifs = ifs_alloc(iter->inode, folio, iter->flags); + if ((iter->flags & IOMAP_NOWAIT) && !ifs && nr_blocks > 1) + return -EAGAIN; + + if (folio_test_uptodate(folio)) + return 0; + + do { + iomap_adjust_read_range(iter->inode, folio, &block_start, + block_end - block_start, &poff, &plen); + if (plen == 0) + break; + + /* + * If the read range will be entirely overwritten by the write, + * we can skip having to zero/read it in. + */ + if (!(iter->flags & IOMAP_UNSHARE) && from <= poff && + to >= poff + plen) + continue; + + if (iomap_block_needs_zeroing(iter, block_start)) { + if (WARN_ON_ONCE(iter->flags & IOMAP_UNSHARE)) + return -EIO; + folio_zero_segments(folio, poff, from, to, poff + plen); + } else { + const struct iomap *iomap = iomap_iter_srcmap(iter); + int status; + + if (iter->flags & IOMAP_NOWAIT) + return -EAGAIN; + + if (write_ops && write_ops->read_folio_range) + status = write_ops->read_folio_range(iter, + folio, block_start, plen); + else + status = iomap_bio_read_folio_range_sync(iter, + folio, block_start, plen); + if (status < 0) + fserror_report_io(iter->inode, + FSERR_BUFFERED_READ, pos, + plen, status, GFP_NOFS); + if (status) + return status; + + if (iomap->flags & IOMAP_F_ZERO_TAIL) + folio_zero_segment(folio, to, poff + plen); + } + iomap_set_range_uptodate(folio, poff, plen); + } while ((block_start += plen) < block_end); + + return 0; +} + +static struct folio *__iomap_get_folio(struct iomap_iter *iter, + const struct iomap_write_ops *write_ops, size_t len) +{ + loff_t pos = iter->pos; + + if (!mapping_large_folio_support(iter->inode->i_mapping)) + len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos)); + + if (iter->iomap.flags & IOMAP_F_FOLIO_BATCH) { + struct folio *folio = folio_batch_next(iter->fbatch); + + if (!folio) + return NULL; + + /* + * The folio mapping generally shouldn't have changed based on + * fs locks, but be consistent with filemap lookup and retry + * the iter if it does. + */ + folio_lock(folio); + if (unlikely(folio->mapping != iter->inode->i_mapping)) { + iter->iomap.flags |= IOMAP_F_STALE; + folio_unlock(folio); + return NULL; + } + + folio_get(folio); + folio_wait_stable(folio); + return folio; + } + + if (write_ops && write_ops->get_folio) + return write_ops->get_folio(iter, pos, len); + return iomap_get_folio(iter, pos, len); +} + +static void __iomap_put_folio(struct iomap_iter *iter, + const struct iomap_write_ops *write_ops, size_t ret, + struct folio *folio) +{ + loff_t pos = iter->pos; + + if (write_ops && write_ops->put_folio) { + write_ops->put_folio(iter->inode, pos, ret, folio); + } else { + folio_unlock(folio); + folio_put(folio); + } +} + +/* trim pos and bytes to within a given folio */ +static loff_t iomap_trim_folio_range(struct iomap_iter *iter, + struct folio *folio, size_t *offset, u64 *bytes) +{ + loff_t pos = iter->pos; + size_t fsize = folio_size(folio); + + WARN_ON_ONCE(pos < folio_pos(folio)); + WARN_ON_ONCE(pos >= folio_pos(folio) + fsize); + + *offset = offset_in_folio(folio, pos); + *bytes = min(*bytes, fsize - *offset); + + return pos; +} + +static int iomap_write_begin_inline(const struct iomap_iter *iter, + struct folio *folio) +{ + /* 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, folio); +} + +/* + * Grab and prepare a folio for write based on iter state. Returns the folio, + * offset, and length. Callers can optionally pass a max length *plen, + * otherwise init to zero. + */ +static int iomap_write_begin(struct iomap_iter *iter, + const struct iomap_write_ops *write_ops, struct folio **foliop, + size_t *poffset, u64 *plen) +{ + const struct iomap *srcmap = iomap_iter_srcmap(iter); + loff_t pos; + u64 len = min_t(u64, SIZE_MAX, iomap_length(iter)); + struct folio *folio; + int status = 0; + + len = min_not_zero(len, *plen); + *foliop = NULL; + *plen = 0; + + if (fatal_signal_pending(current)) + return -EINTR; + + folio = __iomap_get_folio(iter, write_ops, len); + if (IS_ERR(folio)) + return PTR_ERR(folio); + + /* + * No folio means we're done with a batch. We still have range to + * process so return and let the caller iterate and refill the batch. + */ + if (!folio) { + WARN_ON_ONCE(!(iter->iomap.flags & IOMAP_F_FOLIO_BATCH)); + return 0; + } + + /* + * Now we have a locked folio, before we do anything with it we need to + * check that the iomap we have cached is not stale. The inode extent + * mapping can change due to concurrent IO in flight (e.g. + * IOMAP_UNWRITTEN state can change and memory reclaim could have + * reclaimed a previously partially written page at this index after IO + * completion before this write reaches this file offset) and hence we + * could do the wrong thing here (zero a page range incorrectly or fail + * to zero) and corrupt data. + */ + if (write_ops && write_ops->iomap_valid) { + bool iomap_valid = write_ops->iomap_valid(iter->inode, + &iter->iomap); + if (!iomap_valid) { + iter->iomap.flags |= IOMAP_F_STALE; + status = 0; + goto out_unlock; + } + } + + /* + * The folios in a batch may not be contiguous. If we've skipped + * forward, advance the iter to the pos of the current folio. If the + * folio starts beyond the end of the mapping, it may have been trimmed + * since the lookup for whatever reason. Return a NULL folio to + * terminate the op. + */ + if (folio_pos(folio) > iter->pos) { + len = min_t(u64, folio_pos(folio) - iter->pos, + iomap_length(iter)); + status = iomap_iter_advance(iter, len); + len = iomap_length(iter); + if (status || !len) + goto out_unlock; + } + + pos = iomap_trim_folio_range(iter, folio, poffset, &len); + + if (srcmap->type == IOMAP_INLINE) + status = iomap_write_begin_inline(iter, folio); + else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) + status = __block_write_begin_int(folio, pos, len, NULL, srcmap); + else + status = __iomap_write_begin(iter, write_ops, len, folio); + + if (unlikely(status)) + goto out_unlock; + + *foliop = folio; + *plen = len; + return 0; + +out_unlock: + __iomap_put_folio(iter, write_ops, 0, folio); + return status; +} + +static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len, + size_t copied, struct folio *folio) +{ + flush_dcache_folio(folio); + + /* + * The blocks that were entirely written will now be uptodate, so we + * don't have to worry about a read_folio 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 + * read_folio 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 && !folio_test_uptodate(folio))) + return false; + iomap_set_range_uptodate(folio, offset_in_folio(folio, pos), len); + iomap_set_range_dirty(folio, offset_in_folio(folio, pos), copied); + filemap_dirty_folio(inode->i_mapping, folio); + return true; +} + +static bool iomap_write_end_inline(const struct iomap_iter *iter, + struct folio *folio, loff_t pos, size_t copied) +{ + const struct iomap *iomap = &iter->iomap; + void *addr; + + WARN_ON_ONCE(!folio_test_uptodate(folio)); + + if (WARN_ON_ONCE(!iomap->inline_data)) + return false; + + flush_dcache_folio(folio); + addr = kmap_local_folio(folio, pos); + memcpy(iomap_inline_data(iomap, pos), addr, copied); + kunmap_local(addr); + + mark_inode_dirty(iter->inode); + return true; +} + +/* + * Returns true if all copied bytes have been written to the pagecache, + * otherwise return false. + */ +static bool iomap_write_end(struct iomap_iter *iter, size_t len, size_t copied, + struct folio *folio) +{ + const struct iomap *srcmap = iomap_iter_srcmap(iter); + loff_t pos = iter->pos; + + if (srcmap->type == IOMAP_INLINE) + return iomap_write_end_inline(iter, folio, pos, copied); + + if (srcmap->flags & IOMAP_F_BUFFER_HEAD) { + size_t bh_written; + + bh_written = block_write_end(pos, len, copied, folio); + WARN_ON_ONCE(bh_written != copied && bh_written != 0); + return bh_written == copied; + } + + return __iomap_write_end(iter->inode, pos, len, copied, folio); +} + +static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i, + const struct iomap_write_ops *write_ops) +{ + int status = 0; + struct address_space *mapping = iter->inode->i_mapping; + size_t chunk = mapping_max_folio_size(mapping); + unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0; + + do { + struct folio *folio; + loff_t old_size; + size_t offset; /* Offset into folio */ + u64 bytes; /* Bytes to write to folio */ + size_t copied; /* Bytes copied from user */ + u64 written; /* Bytes have been written */ + loff_t pos; + + bytes = iov_iter_count(i); +retry: + offset = iter->pos & (chunk - 1); + bytes = min(chunk - offset, bytes); + status = balance_dirty_pages_ratelimited_flags(mapping, + bdp_flags); + if (unlikely(status)) + break; + + if (bytes > iomap_length(iter)) + bytes = iomap_length(iter); + + /* + * 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. + * + * For async buffered writes the assumption is that the user + * page has already been faulted in. This can be optimized by + * faulting the user page. + */ + if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) { + status = -EFAULT; + break; + } + + status = iomap_write_begin(iter, write_ops, &folio, &offset, + &bytes); + if (unlikely(status)) { + iomap_write_failed(iter->inode, iter->pos, bytes); + break; + } + if (iter->iomap.flags & IOMAP_F_STALE) + break; + + pos = iter->pos; + + if (mapping_writably_mapped(mapping)) + flush_dcache_folio(folio); + + copied = copy_folio_from_iter_atomic(folio, offset, bytes, i); + written = iomap_write_end(iter, bytes, copied, folio) ? + copied : 0; + + /* + * 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. Only once that's done can we + * unlock and release the folio. + */ + old_size = iter->inode->i_size; + if (pos + written > old_size && + !(iter->iomap.flags & IOMAP_F_FSVERITY)) { + i_size_write(iter->inode, pos + written); + iter->iomap.flags |= IOMAP_F_SIZE_CHANGED; + } + __iomap_put_folio(iter, write_ops, written, folio); + + if (old_size < pos && !(iter->iomap.flags & IOMAP_F_FSVERITY)) + pagecache_isize_extended(iter->inode, old_size, pos); + + cond_resched(); + if (unlikely(written == 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. + */ + iomap_write_failed(iter->inode, pos, bytes); + iov_iter_revert(i, copied); + + if (chunk > PAGE_SIZE) + chunk /= 2; + if (copied) { + bytes = copied; + goto retry; + } + } else { + iomap_iter_advance(iter, written); + } + } while (iov_iter_count(i) && iomap_length(iter)); + + return status; +} + +ssize_t +iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, + const struct iomap_ops *ops, + const struct iomap_write_ops *write_ops, void *private) +{ + struct iomap_iter iter = { + .inode = iocb->ki_filp->f_mapping->host, + .pos = iocb->ki_pos, + .len = iov_iter_count(i), + .flags = IOMAP_WRITE, + .private = private, + }; + ssize_t ret; + + if (iocb->ki_flags & IOCB_NOWAIT) + iter.flags |= IOMAP_NOWAIT; + if (iocb->ki_flags & IOCB_DONTCACHE) + iter.flags |= IOMAP_DONTCACHE; + + while ((ret = iomap_iter(&iter, ops)) > 0) + iter.status = iomap_write_iter(&iter, i, write_ops); + + if (unlikely(iter.pos == iocb->ki_pos)) + return ret; + ret = iter.pos - iocb->ki_pos; + iocb->ki_pos = iter.pos; + return ret; +} +EXPORT_SYMBOL_GPL(iomap_file_buffered_write); + +int iomap_fsverity_write(struct file *file, loff_t pos, size_t length, + const void *buf, const struct iomap_ops *ops, + const struct iomap_write_ops *write_ops) +{ + int ret; + struct iov_iter iiter; + struct kvec kvec = { + .iov_base = (void *)buf, + .iov_len = length, + }; + struct kiocb iocb = { + .ki_filp = file, + .ki_ioprio = get_current_ioprio(), + .ki_pos = pos, + }; + + iov_iter_kvec(&iiter, WRITE, &kvec, 1, length); + + ret = iomap_file_buffered_write(&iocb, &iiter, ops, write_ops, NULL); + if (ret < 0) + return ret; + return ret == length ? 0 : -EIO; +} +EXPORT_SYMBOL_GPL(iomap_fsverity_write); + +static void iomap_write_delalloc_ifs_punch(struct inode *inode, + struct folio *folio, loff_t start_byte, loff_t end_byte, + struct iomap *iomap, iomap_punch_t punch) +{ + unsigned int first_blk, last_blk; + loff_t last_byte; + u8 blkbits = inode->i_blkbits; + struct iomap_folio_state *ifs; + + /* + * When we have per-block dirty tracking, there can be + * blocks within a folio which are marked uptodate + * but not dirty. In that case it is necessary to punch + * out such blocks to avoid leaking any delalloc blocks. + */ + ifs = folio->private; + if (!ifs) + return; + + last_byte = min_t(loff_t, end_byte - 1, folio_next_pos(folio) - 1); + first_blk = offset_in_folio(folio, start_byte) >> blkbits; + last_blk = offset_in_folio(folio, last_byte) >> blkbits; + while ((first_blk = ifs_next_clean_block(folio, first_blk, last_blk)) + <= last_blk) { + punch(inode, folio_pos(folio) + (first_blk << blkbits), + 1 << blkbits, iomap); + first_blk++; + } +} + +static void iomap_write_delalloc_punch(struct inode *inode, struct folio *folio, + loff_t *punch_start_byte, loff_t start_byte, loff_t end_byte, + struct iomap *iomap, iomap_punch_t punch) +{ + if (!folio_test_dirty(folio)) + return; + + /* if dirty, punch up to offset */ + if (start_byte > *punch_start_byte) { + punch(inode, *punch_start_byte, start_byte - *punch_start_byte, + iomap); + } + + /* Punch non-dirty blocks within folio */ + iomap_write_delalloc_ifs_punch(inode, folio, start_byte, end_byte, + iomap, punch); + + /* + * Make sure the next punch start is correctly bound to + * the end of this data range, not the end of the folio. + */ + *punch_start_byte = min_t(loff_t, end_byte, folio_next_pos(folio)); +} + +/* + * Scan the data range passed to us for dirty page cache folios. If we find a + * dirty folio, punch out the preceding range and update the offset from which + * the next punch will start from. + * + * We can punch out storage reservations under clean pages because they either + * contain data that has been written back - in which case the delalloc punch + * over that range is a no-op - or they have been read faults in which case they + * contain zeroes and we can remove the delalloc backing range and any new + * writes to those pages will do the normal hole filling operation... + * + * This makes the logic simple: we only need to keep the delalloc extents only + * over the dirty ranges of the page cache. + * + * This function uses [start_byte, end_byte) intervals (i.e. open ended) to + * simplify range iterations. + */ +static void iomap_write_delalloc_scan(struct inode *inode, + loff_t *punch_start_byte, loff_t start_byte, loff_t end_byte, + struct iomap *iomap, iomap_punch_t punch) +{ + while (start_byte < end_byte) { + struct folio *folio; + + /* grab locked page */ + folio = filemap_lock_folio(inode->i_mapping, + start_byte >> PAGE_SHIFT); + if (IS_ERR(folio)) { + start_byte = ALIGN_DOWN(start_byte, PAGE_SIZE) + + PAGE_SIZE; + continue; + } + + iomap_write_delalloc_punch(inode, folio, punch_start_byte, + start_byte, end_byte, iomap, punch); + + /* move offset to start of next folio in range */ + start_byte = folio_next_pos(folio); + folio_unlock(folio); + folio_put(folio); + } +} + +/* + * When a short write occurs, the filesystem might need to use ->iomap_end + * to remove space reservations created in ->iomap_begin. + * + * For filesystems that use delayed allocation, there can be dirty pages over + * the delalloc extent outside the range of a short write but still within the + * delalloc extent allocated for this iomap if the write raced with page + * faults. + * + * Punch out all the delalloc blocks in the range given except for those that + * have dirty data still pending in the page cache - those are going to be + * written and so must still retain the delalloc backing for writeback. + * + * The punch() callback *must* only punch delalloc extents in the range passed + * to it. It must skip over all other types of extents in the range and leave + * them completely unchanged. It must do this punch atomically with respect to + * other extent modifications. + * + * The punch() callback may be called with a folio locked to prevent writeback + * extent allocation racing at the edge of the range we are currently punching. + * The locked folio may or may not cover the range being punched, so it is not + * safe for the punch() callback to lock folios itself. + * + * Lock order is: + * + * inode->i_rwsem (shared or exclusive) + * inode->i_mapping->invalidate_lock (exclusive) + * folio_lock() + * ->punch + * internal filesystem allocation lock + * + * As we are scanning the page cache for data, we don't need to reimplement the + * wheel - mapping_seek_hole_data() does exactly what we need to identify the + * start and end of data ranges correctly even for sub-folio block sizes. This + * byte range based iteration is especially convenient because it means we + * don't have to care about variable size folios, nor where the start or end of + * the data range lies within a folio, if they lie within the same folio or even + * if there are multiple discontiguous data ranges within the folio. + * + * It should be noted that mapping_seek_hole_data() is not aware of EOF, and so + * can return data ranges that exist in the cache beyond EOF. e.g. a page fault + * spanning EOF will initialise the post-EOF data to zeroes and mark it up to + * date. A write page fault can then mark it dirty. If we then fail a write() + * beyond EOF into that up to date cached range, we allocate a delalloc block + * beyond EOF and then have to punch it out. Because the range is up to date, + * mapping_seek_hole_data() will return it, and we will skip the punch because + * the folio is dirty. THis is incorrect - we always need to punch out delalloc + * beyond EOF in this case as writeback will never write back and covert that + * delalloc block beyond EOF. Hence we limit the cached data scan range to EOF, + * resulting in always punching out the range from the EOF to the end of the + * range the iomap spans. + * + * Intervals are of the form [start_byte, end_byte) (i.e. open ended) because it + * matches the intervals returned by mapping_seek_hole_data(). i.e. SEEK_DATA + * returns the start of a data range (start_byte), and SEEK_HOLE(start_byte) + * returns the end of the data range (data_end). Using closed intervals would + * require sprinkling this code with magic "+ 1" and "- 1" arithmetic and expose + * the code to subtle off-by-one bugs.... + */ +void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte, + loff_t end_byte, unsigned flags, struct iomap *iomap, + iomap_punch_t punch) +{ + loff_t punch_start_byte = start_byte; + loff_t scan_end_byte = min(i_size_read(inode), end_byte); + + /* + * The caller must hold invalidate_lock to avoid races with page faults + * re-instantiating folios and dirtying them via ->page_mkwrite whilst + * we walk the cache and perform delalloc extent removal. Failing to do + * this can leave dirty pages with no space reservation in the cache. + */ + lockdep_assert_held_write(&inode->i_mapping->invalidate_lock); + + while (start_byte < scan_end_byte) { + loff_t data_end; + + start_byte = mapping_seek_hole_data(inode->i_mapping, + start_byte, scan_end_byte, SEEK_DATA); + /* + * If there is no more data to scan, all that is left is to + * punch out the remaining range. + * + * Note that mapping_seek_hole_data is only supposed to return + * either an offset or -ENXIO, so WARN on any other error as + * that would be an API change without updating the callers. + */ + if (start_byte == -ENXIO || start_byte == scan_end_byte) + break; + if (WARN_ON_ONCE(start_byte < 0)) + return; + WARN_ON_ONCE(start_byte < punch_start_byte); + WARN_ON_ONCE(start_byte > scan_end_byte); + + /* + * We find the end of this contiguous cached data range by + * seeking from start_byte to the beginning of the next hole. + */ + data_end = mapping_seek_hole_data(inode->i_mapping, start_byte, + scan_end_byte, SEEK_HOLE); + if (WARN_ON_ONCE(data_end < 0)) + return; + + /* + * If we race with post-direct I/O invalidation of the page cache, + * there might be no data left at start_byte. + */ + if (data_end == start_byte) + continue; + + WARN_ON_ONCE(data_end < start_byte); + WARN_ON_ONCE(data_end > scan_end_byte); + + iomap_write_delalloc_scan(inode, &punch_start_byte, start_byte, + data_end, iomap, punch); + + /* The next data search starts at the end of this one. */ + start_byte = data_end; + } + + if (punch_start_byte < end_byte) + punch(inode, punch_start_byte, end_byte - punch_start_byte, + iomap); +} +EXPORT_SYMBOL_GPL(iomap_write_delalloc_release); + +static int iomap_unshare_iter(struct iomap_iter *iter, + const struct iomap_write_ops *write_ops) +{ + struct iomap *iomap = &iter->iomap; + u64 bytes = iomap_length(iter); + int status; + + if (!iomap_want_unshare_iter(iter)) + return iomap_iter_advance(iter, bytes); + + do { + struct folio *folio; + size_t offset; + bool ret; + + bytes = min_t(u64, SIZE_MAX, bytes); + status = iomap_write_begin(iter, write_ops, &folio, &offset, + &bytes); + if (unlikely(status)) + return status; + if (iomap->flags & IOMAP_F_STALE) + break; + + ret = iomap_write_end(iter, bytes, bytes, folio); + __iomap_put_folio(iter, write_ops, bytes, folio); + if (WARN_ON_ONCE(!ret)) + return -EIO; + + cond_resched(); + + balance_dirty_pages_ratelimited(iter->inode->i_mapping); + + status = iomap_iter_advance(iter, bytes); + if (status) + break; + } while ((bytes = iomap_length(iter)) > 0); + + return status; +} + +int +iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len, + const struct iomap_ops *ops, + const struct iomap_write_ops *write_ops) +{ + struct iomap_iter iter = { + .inode = inode, + .pos = pos, + .flags = IOMAP_WRITE | IOMAP_UNSHARE, + }; + loff_t size = i_size_read(inode); + int ret; + + if (pos < 0 || pos >= size) + return 0; + + iter.len = min(len, size - pos); + while ((ret = iomap_iter(&iter, ops)) > 0) + iter.status = iomap_unshare_iter(&iter, write_ops); + return ret; +} +EXPORT_SYMBOL_GPL(iomap_file_unshare); + +/* + * Flush the remaining range of the iter and mark the current mapping stale. + * This is used when zero range sees an unwritten mapping that may have had + * dirty pagecache over it. + */ +static inline int iomap_zero_iter_flush_and_stale(struct iomap_iter *i) +{ + struct address_space *mapping = i->inode->i_mapping; + loff_t end = i->pos + i->len - 1; + + i->iomap.flags |= IOMAP_F_STALE; + return filemap_write_and_wait_range(mapping, i->pos, end); +} + +static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero, + const struct iomap_write_ops *write_ops) +{ + u64 bytes = iomap_length(iter); + bool zeroed = false; + int status; + + do { + struct folio *folio; + size_t offset; + bool ret; + + balance_dirty_pages_ratelimited(iter->inode->i_mapping); + + bytes = min_t(u64, SIZE_MAX, bytes); + status = iomap_write_begin(iter, write_ops, &folio, &offset, + &bytes); + if (status) + return status; + if (iter->iomap.flags & IOMAP_F_STALE) + break; + + /* a NULL folio means we're done with a folio batch */ + if (!folio) { + status = iomap_iter_advance_full(iter); + if (status) + return status; + break; + } + + /* warn about zeroing folios beyond eof that won't write back */ + WARN_ON_ONCE(folio_pos(folio) > iter->inode->i_size); + + trace_iomap_zero_iter(iter->inode, folio_pos(folio) + offset, + bytes); + + folio_zero_range(folio, offset, bytes); + zeroed = true; + folio_mark_accessed(folio); + + ret = iomap_write_end(iter, bytes, bytes, folio); + __iomap_put_folio(iter, write_ops, bytes, folio); + if (WARN_ON_ONCE(!ret)) + return -EIO; + + status = iomap_iter_advance(iter, bytes); + if (status) + return status; + } while ((bytes = iomap_length(iter)) > 0); + + if (did_zero && zeroed) + *did_zero = true; + return status; +} + +/** + * iomap_fill_dirty_folios - fill a folio batch with dirty folios + * @iter: Iteration structure + * @start: Start offset of range. Updated based on lookup progress. + * @end: End offset of range + * @iomap_flags: Flags to set on the associated iomap to track the batch. + * + * Returns the folio count directly. Also returns the associated control flag if + * the the batch lookup is performed and the expected offset of a subsequent + * lookup via out params. The caller is responsible to set the flag on the + * associated iomap. + */ +unsigned int +iomap_fill_dirty_folios( + struct iomap_iter *iter, + loff_t *start, + loff_t end, + unsigned int *iomap_flags) +{ + struct address_space *mapping = iter->inode->i_mapping; + pgoff_t pstart = *start >> PAGE_SHIFT; + pgoff_t pend = (end - 1) >> PAGE_SHIFT; + unsigned int count; + + if (!iter->fbatch) { + *start = end; + return 0; + } + + count = filemap_get_folios_dirty(mapping, &pstart, pend, iter->fbatch); + *start = (pstart << PAGE_SHIFT); + *iomap_flags |= IOMAP_F_FOLIO_BATCH; + return count; +} +EXPORT_SYMBOL_GPL(iomap_fill_dirty_folios); + +int +iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, + const struct iomap_ops *ops, + const struct iomap_write_ops *write_ops, void *private) +{ + struct folio_batch fbatch; + struct iomap_iter iter = { + .inode = inode, + .pos = pos, + .len = len, + .flags = IOMAP_ZERO, + .private = private, + .fbatch = &fbatch, + }; + struct address_space *mapping = inode->i_mapping; + int ret; + bool range_dirty; + + folio_batch_init(&fbatch); + + /* + * To avoid an unconditional flush, check pagecache state and only flush + * if dirty and the fs returns a mapping that might convert on + * writeback. + */ + range_dirty = filemap_range_needs_writeback(mapping, iter.pos, + iter.pos + iter.len - 1); + while ((ret = iomap_iter(&iter, ops)) > 0) { + const struct iomap *srcmap = iomap_iter_srcmap(&iter); + + if (!(iter.iomap.flags & IOMAP_F_FOLIO_BATCH) && + (srcmap->type == IOMAP_HOLE || + srcmap->type == IOMAP_UNWRITTEN)) { + s64 status; + + if (range_dirty && srcmap->type == IOMAP_UNWRITTEN) { + range_dirty = false; + status = iomap_zero_iter_flush_and_stale(&iter); + } else { + status = iomap_iter_advance_full(&iter); + } + iter.status = status; + continue; + } + + iter.status = iomap_zero_iter(&iter, did_zero, write_ops); + } + 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, + const struct iomap_write_ops *write_ops, void *private) +{ + 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, + write_ops, private); +} +EXPORT_SYMBOL_GPL(iomap_truncate_page); + +static int iomap_folio_mkwrite_iter(struct iomap_iter *iter, + struct folio *folio) +{ + loff_t length = iomap_length(iter); + int ret; + + if (iter->iomap.flags & IOMAP_F_BUFFER_HEAD) { + ret = __block_write_begin_int(folio, iter->pos, length, NULL, + &iter->iomap); + if (ret) + return ret; + block_commit_write(folio, 0, length); + } else { + WARN_ON_ONCE(!folio_test_uptodate(folio)); + folio_mark_dirty(folio); + } + + return iomap_iter_advance(iter, length); +} + +vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops, + void *private) +{ + struct iomap_iter iter = { + .inode = file_inode(vmf->vma->vm_file), + .flags = IOMAP_WRITE | IOMAP_FAULT, + .private = private, + }; + struct folio *folio = page_folio(vmf->page); + ssize_t ret; + + folio_lock(folio); + ret = folio_mkwrite_check_truncate(folio, iter.inode); + if (ret < 0) + goto out_unlock; + iter.pos = folio_pos(folio); + iter.len = ret; + while ((ret = iomap_iter(&iter, ops)) > 0) + iter.status = iomap_folio_mkwrite_iter(&iter, folio); + + if (ret < 0) + goto out_unlock; + folio_wait_stable(folio); + return VM_FAULT_LOCKED; +out_unlock: + folio_unlock(folio); + return vmf_fs_error(ret); +} +EXPORT_SYMBOL_GPL(iomap_page_mkwrite); + +static void iomap_writeback_init(struct inode *inode, struct folio *folio) +{ + struct iomap_folio_state *ifs = folio->private; + + WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs); + if (ifs) { + WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending) != 0); + /* + * Set this to the folio size. After processing the folio for + * writeback in iomap_writeback_folio(), we'll subtract any + * ranges not written back. + * + * We do this because otherwise, we would have to atomically + * increment ifs->write_bytes_pending every time a range in the + * folio needs to be written back. + */ + atomic_set(&ifs->write_bytes_pending, folio_size(folio)); + } +} + +void iomap_finish_folio_write(struct inode *inode, struct folio *folio, + size_t len) +{ + struct iomap_folio_state *ifs = folio->private; + + WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs); + WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) <= 0); + + if (!ifs || atomic_sub_and_test(len, &ifs->write_bytes_pending)) + folio_end_writeback(folio); +} +EXPORT_SYMBOL_GPL(iomap_finish_folio_write); + +static int iomap_writeback_range(struct iomap_writepage_ctx *wpc, + struct folio *folio, u64 pos, u32 rlen, u64 end_pos, + size_t *bytes_submitted) +{ + do { + ssize_t ret; + + ret = wpc->ops->writeback_range(wpc, folio, pos, rlen, end_pos); + if (WARN_ON_ONCE(ret == 0 || ret > rlen)) + return -EIO; + if (ret < 0) + return ret; + rlen -= ret; + pos += ret; + + /* + * Holes are not written back by ->writeback_range, so track + * if we did handle anything that is not a hole here. + */ + if (wpc->iomap.type != IOMAP_HOLE) + *bytes_submitted += ret; + } while (rlen); + + return 0; +} + +/* + * Check interaction of the folio with the file end. + * + * If the folio is entirely beyond i_size, return false. If it straddles + * i_size, adjust end_pos and zero all data beyond i_size. Don't skip fsverity + * folios as those are beyond i_size. + */ +static bool iomap_writeback_handle_eof(struct folio *folio, + struct iomap_writepage_ctx *wpc, u64 *end_pos) +{ + struct inode *inode = wpc->inode; + u64 isize = i_size_read(inode); + + if (wpc->iomap.flags & IOMAP_F_FSVERITY) { + WARN_ON_ONCE(folio_pos(folio) < isize); + return true; + } + + if (*end_pos > isize) { + size_t poff = offset_in_folio(folio, isize); + pgoff_t end_index = isize >> PAGE_SHIFT; + + /* + * If the folio is entirely ouside of i_size, skip it. + * + * This can happen due to a truncate operation that is in + * progress and in that case truncate will finish it off once + * we've dropped the folio lock. + * + * Note that the pgoff_t used for end_index is an unsigned long. + * If the given offset is greater than 16TB on a 32-bit system, + * then if we checked if the folio is fully outside i_size with + * "if (folio->index >= end_index + 1)", "end_index + 1" would + * overflow and evaluate to 0. Hence this folio 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 folio is totally beyond i_size or if its + * offset is just equal to the EOF. + */ + if (folio->index > end_index || + (folio->index == end_index && poff == 0)) + return false; + + /* + * The folio 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. + * + * Also adjust the end_pos to the end of file and skip writeback + * for all blocks entirely beyond i_size. + */ + folio_zero_segment(folio, poff, folio_size(folio)); + *end_pos = isize; + } + + return true; +} + +int iomap_writeback_folio(struct iomap_writepage_ctx *wpc, struct folio *folio) +{ + struct iomap_folio_state *ifs = folio->private; + struct inode *inode = wpc->inode; + u64 pos = folio_pos(folio); + u64 end_pos = pos + folio_size(folio); + u64 end_aligned = 0; + loff_t orig_pos = pos; + size_t bytes_submitted = 0; + int error = 0; + u32 rlen; + + WARN_ON_ONCE(!folio_test_locked(folio)); + WARN_ON_ONCE(folio_test_dirty(folio)); + WARN_ON_ONCE(folio_test_writeback(folio)); + + trace_iomap_writeback_folio(inode, pos, folio_size(folio)); + + if (!iomap_writeback_handle_eof(folio, wpc, &end_pos)) + return 0; + WARN_ON_ONCE(end_pos <= pos); + + if (i_blocks_per_folio(inode, folio) > 1) { + if (!ifs) { + ifs = ifs_alloc(inode, folio, 0); + iomap_set_range_dirty(folio, 0, end_pos - pos); + } + + iomap_writeback_init(inode, folio); + } + + /* + * Set the writeback bit ASAP, as the I/O completion for the single + * block per folio case happen hit as soon as we're submitting the bio. + */ + folio_start_writeback(folio); + + /* + * Walk through the folio to find dirty areas to write back. + */ + end_aligned = round_up(end_pos, i_blocksize(inode)); + while ((rlen = iomap_find_dirty_range(folio, &pos, end_aligned))) { + error = iomap_writeback_range(wpc, folio, pos, rlen, end_pos, + &bytes_submitted); + if (error) + break; + pos += rlen; + } + + if (bytes_submitted) + wpc->nr_folios++; + if (error && pos > orig_pos) + fserror_report_io(inode, FSERR_BUFFERED_WRITE, orig_pos, 0, + error, GFP_NOFS); + + /* + * We can have dirty bits set past end of file in page_mkwrite path + * while mapping the last partial folio. Hence it's better to clear + * all the dirty bits in the folio here. + */ + iomap_clear_range_dirty(folio, 0, folio_size(folio)); + + /* + * Usually the writeback bit is cleared by the I/O completion handler. + * But we may end up either not actually writing any blocks, or (when + * there are multiple blocks in a folio) all I/O might have finished + * already at this point. In that case we need to clear the writeback + * bit ourselves right after unlocking the page. + */ + if (ifs) { + /* + * Subtract any bytes that were initially accounted to + * write_bytes_pending but skipped for writeback. + */ + size_t bytes_not_submitted = folio_size(folio) - + bytes_submitted; + + if (bytes_not_submitted) + iomap_finish_folio_write(inode, folio, + bytes_not_submitted); + } else if (!bytes_submitted) { + folio_end_writeback(folio); + } + + mapping_set_error(inode->i_mapping, error); + return error; +} +EXPORT_SYMBOL_GPL(iomap_writeback_folio); + +int +iomap_writepages(struct iomap_writepage_ctx *wpc) +{ + struct address_space *mapping = wpc->inode->i_mapping; + struct folio *folio = NULL; + int error; + + /* + * Writeback from reclaim context should never happen except in the case + * of a VM regression so warn about it and refuse to write the data. + */ + if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC | PF_KSWAPD)) == + PF_MEMALLOC)) + return -EIO; + + while ((folio = writeback_iter(mapping, wpc->wbc, folio, &error))) { + error = iomap_writeback_folio(wpc, folio); + folio_unlock(folio); + } + + /* + * 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. + * + * We cannot cancel the writeback directly in that case, so always call + * ->writeback_submit to run the I/O completion handler to clear the + * writeback bit and let the file system proess the errors. + */ + if (wpc->wb_ctx) + return wpc->ops->writeback_submit(wpc, error); + return error; +} +EXPORT_SYMBOL_GPL(iomap_writepages); |