// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2010 Red Hat, Inc.
* Copyright (C) 2016-2023 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"
#define IOEND_BATCH_SIZE 4096
/*
* 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 struct bio_set iomap_ioend_bioset;
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));
}
static inline bool ifs_block_is_uptodate(struct iomap_folio_state *ifs,
unsigned int block)
{
return test_bit(block, ifs->state);
}
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 = off >> inode->i_blkbits;
unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
unsigned int nr_blks = last_blk - first_blk + 1;
bitmap_set(ifs->state, first_blk, nr_blks);
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 uptodate = true;
if (ifs) {
spin_lock_irqsave(&ifs->state_lock, flags);
uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
spin_unlock_irqrestore(&ifs->state_lock, flags);
}
if (uptodate)
folio_mark_uptodate(folio);
}
static inline bool ifs_block_is_dirty(struct folio *folio,
struct iomap_folio_state *ifs, int block)
{
struct inode *inode = folio->mapping->host;
unsigned int blks_per_folio = i_blocks_per_folio(inode, folio);
return test_bit(block + blks_per_folio, ifs->state);
}
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));
unsigned nblks = 1;
while (!ifs_block_is_dirty(folio, ifs, start_blk))
if (++start_blk == end_blk)
return 0;
while (start_blk + nblks < end_blk) {
if (!ifs_block_is_dirty(folio, ifs, start_blk + nblks))
break;
nblks++;
}
*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;
}
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 = (off >> inode->i_blkbits);
unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
unsigned int nr_blks = last_blk - first_blk + 1;
unsigned long flags;
spin_lock_irqsave(&ifs->state_lock, flags);
bitmap_clear(ifs->state, first_blk + blks_per_folio, nr_blks);
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);
}
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 = (off >> inode->i_blkbits);
unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
unsigned int nr_blks = last_blk - first_blk + 1;
unsigned long flags;
spin_lock_irqsave(&ifs->state_lock, flags);
bitmap_set(ifs->state, first_blk + blks_per_folio, nr_blks);
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(struct_size(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 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 i;
/* move forward for each leading block marked uptodate */
for (i = first; i <= last; i++) {
if (!ifs_block_is_uptodate(ifs, i))
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 (ifs_block_is_uptodate(ifs, i)) {
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 + orig_plen > isize) {
unsigned end = offset_in_folio(folio, isize - 1) >> block_bits;
if (first <= end && last > end)
plen -= (last - end) * block_size;
}
*offp = poff;
*lenp = plen;
}
static 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 (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);
}
static void iomap_read_end_io(struct bio *bio)
{
int error = blk_status_to_errno(bio->bi_status);
struct folio_iter fi;
bio_for_each_folio_all(fi, bio)
iomap_finish_folio_read(fi.folio, fi.offset, fi.length, error);
bio_put(bio);
}
struct iomap_readpage_ctx {
struct folio *cur_folio;
bool cur_folio_in_bio;
struct bio *bio;
struct readahead_control *rac;
};
/**
* 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 (folio_test_uptodate(folio))
return 0;
if (WARN_ON_ONCE(size > iomap->length))
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;
}
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 folio *folio = ctx->cur_folio;
struct iomap_folio_state *ifs;
loff_t orig_pos = pos;
size_t poff, plen;
sector_t sector;
if (iomap->type == IOMAP_INLINE)
return iomap_read_inline_data(iter, folio);
/* zero post-eof blocks as the page may be mapped */
ifs = ifs_alloc(iter->inode, folio, iter->flags);
iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, &plen);
if (plen == 0)
goto done;
if (iomap_block_needs_zeroing(iter, pos)) {
folio_zero_range(folio, poff, plen);
iomap_set_range_uptodate(folio, poff, plen);
goto done;
}
ctx->cur_folio_in_bio = true;
if (ifs) {
spin_lock_irq(&ifs->state_lock);
ifs->read_bytes_pending += plen;
spin_unlock_irq(&ifs->state_lock);
}
sector = iomap_sector(iomap, pos);
if (!ctx->bio ||
bio_end_sector(ctx->bio) != sector ||
!bio_add_folio(ctx->bio, folio, plen, poff)) {
gfp_t gfp = mapping_gfp_constraint(folio->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(iomap->bdev, bio_max_segs(nr_vecs),
REQ_OP_READ, gfp);
/*
* 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_read_folio does.
*/
if (!ctx->bio) {
ctx->bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ,
orig_gfp);
}
if (ctx->rac)
ctx->bio->bi_opf |= REQ_RAHEAD;
ctx->bio->bi_iter.bi_sector = sector;
ctx->bio->bi_end_io = iomap_read_end_io;
bio_add_folio_nofail(ctx->bio, folio, 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;
}
static loff_t iomap_read_folio_iter(const struct iomap_iter *iter,
struct iomap_readpage_ctx *ctx)
{
struct folio *folio = ctx->cur_folio;
size_t offset = offset_in_folio(folio, iter->pos);
loff_t length = min_t(loff_t, folio_size(folio) - offset,
iomap_length(iter));
loff_t done, ret;
for (done = 0; done < length; done += ret) {
ret = iomap_readpage_iter(iter, ctx, done);
if (ret <= 0)
return ret;
}
return done;
}
int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
{
struct iomap_iter iter = {
.inode = folio->mapping->host,
.pos = folio_pos(folio),
.len = folio_size(folio),
};
struct iomap_readpage_ctx ctx = {
.cur_folio = folio,
};
int ret;
trace_iomap_readpage(iter.inode, 1);
while ((ret = iomap_iter(&iter, ops)) > 0)
iter.processed = iomap_read_folio_iter(&iter, &ctx);
if (ctx.bio) {
submit_bio(ctx.bio);
WARN_ON_ONCE(!ctx.cur_folio_in_bio);
} else {
WARN_ON_ONCE(ctx.cur_folio_in_bio);
folio_unlock(folio);
}
/*
* Just like mpage_readahead and block_read_full_folio, we always
* return 0 and just set the folio error flag on errors. This
* should be cleaned up throughout the stack eventually.
*/
return 0;
}
EXPORT_SYMBOL_GPL(iomap_read_folio);
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_folio &&
offset_in_folio(ctx->cur_folio, iter->pos + done) == 0) {
if (!ctx->cur_folio_in_bio)
folio_unlock(ctx->cur_folio);
ctx->cur_folio = NULL;
}
if (!ctx->cur_folio) {
ctx->cur_folio = readahead_folio(ctx->rac);
ctx->cur_folio_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_folio) {
if (!ctx.cur_folio_in_bio)
folio_unlock(ctx.cur_folio);
}
}
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, i;
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;
for (i = first; i <= last; i++)
if (!ifs_block_is_uptodate(ifs, i))
return false;
return true;
}
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 | FGP_NOFS;
if (iter->flags & IOMAP_NOWAIT)
fgp |= FGP_NOWAIT;
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);
}
}
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_read_folio_sync(loff_t block_start, struct folio *folio,
size_t poff, size_t plen, const struct iomap *iomap)
{
struct bio_vec bvec;
struct bio bio;
bio_init(&bio, iomap->bdev, &bvec, 1, REQ_OP_READ);
bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
bio_add_folio_nofail(&bio, folio, plen, poff);
return submit_bio_wait(&bio);
}
static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
size_t len, struct folio *folio)
{
const struct iomap *srcmap = iomap_iter_srcmap(iter);
struct iomap_folio_state *ifs;
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_pos(folio) + folio_size(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 (!(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;
folio_zero_segments(folio, poff, from, to, poff + plen);
} else {
int status;
if (iter->flags & IOMAP_NOWAIT)
return -EAGAIN;
status = iomap_read_folio_sync(block_start, folio,
poff, plen, srcmap);
if (status)
return status;
}
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, loff_t pos,
size_t len)
{
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
if (folio_ops && folio_ops->get_folio)
return folio_ops->get_folio(iter, pos, len);
else
return iomap_get_folio(iter, pos, len);
}
static void __iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret,
struct folio *folio)
{
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
if (folio_ops && folio_ops->put_folio) {
folio_ops->put_folio(iter->inode, pos, ret, folio);
} else {
folio_unlock(folio);
folio_put(folio);
}
}
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);
}
static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
size_t len, struct folio **foliop)
{
const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
const struct iomap *srcmap = iomap_iter_srcmap(iter);
struct folio *folio;
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 (!mapping_large_folio_support(iter->inode->i_mapping))
len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
folio = __iomap_get_folio(iter, pos, len);
if (IS_ERR(folio))
return PTR_ERR(folio);
/*
* 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 (folio_ops && folio_ops->iomap_valid) {
bool iomap_valid = folio_ops->iomap_valid(iter->inode,
&iter->iomap);
if (!iomap_valid) {
iter->iomap.flags |= IOMAP_F_STALE;
status = 0;
goto out_unlock;
}
}
if (pos + len > folio_pos(folio) + folio_size(folio))
len = folio_pos(folio) + folio_size(folio) - pos;
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, pos, len, folio);
if (unlikely(status))
goto out_unlock;
*foliop = folio;
return 0;
out_unlock:
__iomap_put_folio(iter, pos, 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 void 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));
BUG_ON(!iomap_inline_data_valid(iomap));
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);
}
/*
* Returns true if all copied bytes have been written to the pagecache,
* otherwise return false.
*/
static bool iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
size_t copied, struct folio *folio)
{
const struct iomap *srcmap = iomap_iter_srcmap(iter);
if (srcmap->type == IOMAP_INLINE) {
iomap_write_end_inline(iter, folio, pos, copied);
return true;
}
if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
size_t bh_written;
bh_written = block_write_end(NULL, iter->inode->i_mapping, pos,
len, copied, folio, NULL);
WARN_ON_ONCE(bh_written != copied && bh_written != 0);
return bh_written == copied;
}
return __iomap_write_end(iter->inode, pos, len, copied, folio);
}
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 total_written = 0;
long 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 */
size_t bytes; /* Bytes to write to folio */
size_t copied; /* Bytes copied from user */
size_t written; /* Bytes have been written */
bytes = iov_iter_count(i);
retry:
offset = pos & (chunk - 1);
bytes = min(chunk - offset, bytes);
status = balance_dirty_pages_ratelimited_flags(mapping,
bdp_flags);
if (unlikely(status))
break;
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.
*
* 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, pos, bytes, &folio);
if (unlikely(status)) {
iomap_write_failed(iter->inode, pos, bytes);
break;
}
if (iter->iomap.flags & IOMAP_F_STALE)
break;
offset = offset_in_folio(folio, pos);
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
if (mapping_writably_mapped(mapping))
flush_dcache_folio(folio);
copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
written = iomap_write_end(iter, pos, 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) {
i_size_write(iter->inode, pos + written);
iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
}
__iomap_put_folio(iter, pos, written, folio);
if (old_size < pos)
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 {
pos += written;
total_written += written;
length -= written;
}
} while (iov_iter_count(i) && length);
if (status == -EAGAIN) {
iov_iter_revert(i, total_written);
return -EAGAIN;
}
return total_written ? total_written : status;
}
ssize_t
iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
const struct iomap_ops *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;
while ((ret = iomap_iter(&iter, ops)) > 0)
iter.processed = iomap_write_iter(&iter, i);
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);
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, i;
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_pos(folio) + folio_size(folio) - 1);
first_blk = offset_in_folio(folio, start_byte) >> blkbits;
last_blk = offset_in_folio(folio, last_byte) >> blkbits;
for (i = first_blk; i <= last_blk; i++) {
if (!ifs_block_is_dirty(folio, ifs, i))
punch(inode, folio_pos(folio) + (i << blkbits),
1 << blkbits, iomap);
}
}
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_pos(folio) + folio_size(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_index(folio) << PAGE_SHIFT;
folio_unlock(folio);
folio_put(folio);
}
}
/*
* 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.
*
* 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....
*/
static 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);
/*
* Lock the mapping 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.
*/
filemap_invalidate_lock(inode->i_mapping);
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))
goto out_unlock;
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))
goto out_unlock;
/*
* 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);
out_unlock:
filemap_invalidate_unlock(inode->i_mapping);
}
/*
* When a short write occurs, the filesystem may need to remove reserved space
* that was allocated in ->iomap_begin from it's ->iomap_end method. For
* filesystems that use delayed allocation, we need to punch out delalloc
* extents from the range that are not dirty in the page cache. As the write can
* race with page faults, 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.
*
* This function uses [start_byte, end_byte) intervals (i.e. open ended) to
* simplify range iterations.
*
* 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
*/
void iomap_file_buffered_write_punch_delalloc(struct inode *inode,
loff_t pos, loff_t length, ssize_t written, unsigned flags,
struct iomap *iomap, iomap_punch_t punch)
{
loff_t start_byte;
loff_t end_byte;
unsigned int blocksize = i_blocksize(inode);
if (iomap->type != IOMAP_DELALLOC)
return;
/* If we didn't reserve the blocks, we're not allowed to punch them. */
if (!(iomap->flags & IOMAP_F_NEW))
return;
/*
* start_byte refers to the first unused block after a short write. If
* nothing was written, round offset down to point at the first block in
* the range.
*/
if (unlikely(!written))
start_byte = round_down(pos, blocksize);
else
start_byte = round_up(pos + written, blocksize);
end_byte = round_up(pos + length, blocksize);
/* Nothing to do if we've written the entire delalloc extent */
if (start_byte >= end_byte)
return;
iomap_write_delalloc_release(inode, start_byte, end_byte, flags, iomap,
punch);
}
EXPORT_SYMBOL_GPL(iomap_file_buffered_write_punch_delalloc);
static loff_t iomap_unshare_iter(struct iomap_iter *iter)
{
struct iomap *iomap = &iter->iomap;
loff_t pos = iter->pos;
loff_t length = iomap_length(iter);
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 delalloc reservations, holes or unwritten extents.
*
* Note that we use srcmap directly instead of iomap_iter_srcmap as
* unsharing requires providing a separate source map, and the presence
* of one is a good indicator that unsharing is needed, unlike
* IOMAP_F_SHARED which can be set for any data that goes into the COW
* fork for XFS.
*/
if (iter->srcmap.type == IOMAP_HOLE ||
iter->srcmap.type == IOMAP_DELALLOC ||
iter->srcmap.type == IOMAP_UNWRITTEN)
return length;
do {
struct folio *folio;
int status;
size_t offset;
size_t bytes = min_t(u64, SIZE_MAX, length);
bool ret;
status = iomap_write_begin(iter, pos, bytes, &folio);
if (unlikely(status))
return status;
if (iomap->flags & IOMAP_F_STALE)
break;
offset = offset_in_folio(folio, pos);
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
ret = iomap_write_end(iter, pos, bytes, bytes, folio);
__iomap_put_folio(iter, pos, bytes, folio);
if (WARN_ON_ONCE(!ret))
return -EIO;
cond_resched();
pos += bytes;
written += bytes;
length -= bytes;
balance_dirty_pages_ratelimited(iter->inode->i_mapping);
} while (length > 0);
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,
.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.processed = iomap_unshare_iter(&iter);
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 loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
bool *range_dirty)
{
const struct iomap *srcmap = iomap_iter_srcmap(iter);
loff_t pos = iter->pos;
loff_t length = iomap_length(iter);
loff_t written = 0;
/*
* We must zero subranges of unwritten mappings that might be dirty in
* pagecache from previous writes. We only know whether the entire range
* was clean or not, however, and dirty folios may have been written
* back or reclaimed at any point after mapping lookup.
*
* The easiest way to deal with this is to flush pagecache to trigger
* any pending unwritten conversions and then grab the updated extents
* from the fs. The flush may change the current mapping, so mark it
* stale for the iterator to remap it for the next pass to handle
* properly.
*
* Note that holes are treated the same as unwritten because zero range
* is (ab)used for partial folio zeroing in some cases. Hole backed
* post-eof ranges can be dirtied via mapped write and the flush
* triggers writeback time post-eof zeroing.
*/
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) {
if (*range_dirty) {
*range_dirty = false;
return iomap_zero_iter_flush_and_stale(iter);
}
/* range is clean and already zeroed, nothing to do */
return length;
}
do {
struct folio *folio;
int status;
size_t offset;
size_t bytes = min_t(u64, SIZE_MAX, length);
bool ret;
status = iomap_write_begin(iter, pos, bytes, &folio);
if (status)
return status;
if (iter->iomap.flags & IOMAP_F_STALE)
break;
offset = offset_in_folio(folio, pos);
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
folio_zero_range(folio, offset, bytes);
folio_mark_accessed(folio);
ret = iomap_write_end(iter, pos, bytes, bytes, folio);
__iomap_put_folio(iter, pos, bytes, folio);
if (WARN_ON_ONCE(!ret))
return -EIO;
pos += bytes;
length -= bytes;
written += bytes;
} while (length > 0);
if (did_zero)
*did_zero = true;
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;
bool range_dirty;
/*
* Zero range wants to skip pre-zeroed (i.e. unwritten) mappings, but
* pagecache must be flushed to ensure stale data from previous
* buffered writes is not exposed. A flush is only required for certain
* types of mappings, but checking pagecache after mapping lookup is
* racy with writeback and reclaim.
*
* Therefore, check the entire range first and pass along whether any
* part of it is dirty. If so and an underlying mapping warrants it,
* flush the cache at that point. This trades off the occasional false
* positive (and spurious flush, if the dirty data and mapping don't
* happen to overlap) for simplicity in handling a relatively uncommon
* situation.
*/
range_dirty = filemap_range_needs_writeback(inode->i_mapping,
pos, pos + len - 1);
while ((ret = iomap_iter(&iter, ops)) > 0)
iter.processed = iomap_zero_iter(&iter, did_zero, &range_dirty);
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_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->page, 0, length);
} else {
WARN_ON_ONCE(!folio_test_uptodate(folio));
folio_mark_dirty(folio);
}
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 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.processed = 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_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);
}
/*
* 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 u32
iomap_finish_ioend(struct iomap_ioend *ioend, int error)
{
struct inode *inode = ioend->io_inode;
struct bio *bio = &ioend->io_bio;
struct folio_iter fi;
u32 folio_count = 0;
if (error) {
mapping_set_error(inode->i_mapping, error);
if (!bio_flagged(bio, BIO_QUIET)) {
pr_err_ratelimited(
"%s: writeback error on inode %lu, offset %lld, sector %llu",
inode->i_sb->s_id, inode->i_ino,
ioend->io_offset, ioend->io_sector);
}
}
/* walk all folios in bio, ending page IO on them */
bio_for_each_folio_all(fi, bio) {
iomap_finish_folio_write(inode, fi.folio, fi.length);
folio_count++;
}
bio_put(bio); /* frees the ioend */
return folio_count;
}
/*
* Ioend completion routine for merged bios. This can only be called from task
* contexts as merged ioends can be of unbound length. Hence we have to break up
* the writeback completions into manageable chunks to avoid long scheduler
* holdoffs. We aim to keep scheduler holdoffs down below 10ms so that we get
* good batch processing throughput without creating adverse scheduler latency
* conditions.
*/
void
iomap_finish_ioends(struct iomap_ioend *ioend, int error)
{
struct list_head tmp;
u32 completions;
might_sleep();
list_replace_init(&ioend->io_list, &tmp);
completions = iomap_finish_ioend(ioend, error);
while (!list_empty(&tmp)) {
if (completions > IOEND_BATCH_SIZE * 8) {
cond_resched();
completions = 0;
}
ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
list_del_init(&ioend->io_list);
completions += 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;
/*
* Do not merge physically discontiguous ioends. The filesystem
* completion functions will have to iterate the physical
* discontiguities even if we merge the ioends at a logical level, so
* we don't gain anything by merging physical discontiguities here.
*
* We cannot use bio->bi_iter.bi_sector here as it is modified during
* submission so does not point to the start sector of the bio at
* completion.
*/
if (ioend->io_sector + (ioend->io_size >> 9) != next->io_sector)
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)
{
iomap_finish_ioend(iomap_ioend_from_bio(bio),
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.
* We cannot cancel ioend directly in that case, so call the bio end I/O handler
* with the error status here to run the normal I/O completion handler to clear
* the writeback bit and let the file system proess the errors.
*/
static int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, int error)
{
if (!wpc->ioend)
return error;
/*
* Let the file systems prepare the I/O submission and hook in an I/O
* comletion handler. This also needs to happen in case after a
* failure happened so that the file system end I/O handler gets called
* to clean up.
*/
if (wpc->ops->prepare_ioend)
error = wpc->ops->prepare_ioend(wpc->ioend, error);
if (error) {
wpc->ioend->io_bio.bi_status = errno_to_blk_status(error);
bio_endio(&wpc->ioend->io_bio);
} else {
submit_bio(&wpc->ioend->io_bio);
}
wpc->ioend = NULL;
return error;
}
static struct iomap_ioend *iomap_alloc_ioend(struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct inode *inode, loff_t pos)
{
struct iomap_ioend *ioend;
struct bio *bio;
bio = bio_alloc_bioset(wpc->iomap.bdev, BIO_MAX_VECS,
REQ_OP_WRITE | wbc_to_write_flags(wbc),
GFP_NOFS, &iomap_ioend_bioset);
bio->bi_iter.bi_sector = iomap_sector(&wpc->iomap, pos);
bio->bi_end_io = iomap_writepage_end_bio;
wbc_init_bio(wbc, bio);
bio->bi_write_hint = inode->i_write_hint;
ioend = iomap_ioend_from_bio(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 = pos;
ioend->io_sector = bio->bi_iter.bi_sector;
wpc->nr_folios = 0;
return ioend;
}
static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t pos)
{
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 (pos != wpc->ioend->io_offset + wpc->ioend->io_size)
return false;
if (iomap_sector(&wpc->iomap, pos) !=
bio_end_sector(&wpc->ioend->io_bio))
return false;
/*
* Limit ioend bio chain lengths to minimise IO completion latency. This
* also prevents long tight loops ending page writeback on all the
* folios in the ioend.
*/
if (wpc->nr_folios >= IOEND_BATCH_SIZE)
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.
*
* If a new ioend is created and cached, the old ioend is submitted to the block
* layer instantly. 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_add_to_ioend(struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct folio *folio,
struct inode *inode, loff_t pos, unsigned len)
{
struct iomap_folio_state *ifs = folio->private;
size_t poff = offset_in_folio(folio, pos);
int error;
if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, pos)) {
new_ioend:
error = iomap_submit_ioend(wpc, 0);
if (error)
return error;
wpc->ioend = iomap_alloc_ioend(wpc, wbc, inode, pos);
}
if (!bio_add_folio(&wpc->ioend->io_bio, folio, len, poff))
goto new_ioend;
if (ifs)
atomic_add(len, &ifs->write_bytes_pending);
wpc->ioend->io_size += len;
wbc_account_cgroup_owner(wbc, &folio->page, len);
return 0;
}
static int iomap_writepage_map_blocks(struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct folio *folio,
struct inode *inode, u64 pos, unsigned dirty_len,
unsigned *count)
{
int error;
do {
unsigned map_len;
error = wpc->ops->map_blocks(wpc, inode, pos, dirty_len);
if (error)
break;
trace_iomap_writepage_map(inode, pos, dirty_len, &wpc->iomap);
map_len = min_t(u64, dirty_len,
wpc->iomap.offset + wpc->iomap.length - pos);
WARN_ON_ONCE(!folio->private && map_len < dirty_len);
switch (wpc->iomap.type) {
case IOMAP_INLINE:
WARN_ON_ONCE(1);
error = -EIO;
break;
case IOMAP_HOLE:
break;
default:
error = iomap_add_to_ioend(wpc, wbc, folio, inode, pos,
map_len);
if (!error)
(*count)++;
break;
}
dirty_len -= map_len;
pos += map_len;
} while (dirty_len && !error);
/*
* 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.
*
* Just let the file system know what portion of the folio failed to
* map.
*/
if (error && wpc->ops->discard_folio)
wpc->ops->discard_folio(folio, pos);
return error;
}
/*
* 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.
*/
static bool iomap_writepage_handle_eof(struct folio *folio, struct inode *inode,
u64 *end_pos)
{
u64 isize = i_size_read(inode);
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 writeback range to skip all blocks entirely
* beyond i_size.
*/
folio_zero_segment(folio, poff, folio_size(folio));
*end_pos = round_up(isize, i_blocksize(inode));
}
return true;
}
static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct folio *folio)
{
struct iomap_folio_state *ifs = folio->private;
struct inode *inode = folio->mapping->host;
u64 pos = folio_pos(folio);
u64 end_pos = pos + folio_size(folio);
unsigned count = 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_writepage(inode, pos, folio_size(folio));
if (!iomap_writepage_handle_eof(folio, inode, &end_pos)) {
folio_unlock(folio);
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);
}
/*
* Keep the I/O completion handler from clearing the writeback
* bit until we have submitted all blocks by adding a bias to
* ifs->write_bytes_pending, which is dropped after submitting
* all blocks.
*/
WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending) != 0);
atomic_inc(&ifs->write_bytes_pending);
}
/*
* 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.
*/
while ((rlen = iomap_find_dirty_range(folio, &pos, end_pos))) {
error = iomap_writepage_map_blocks(wpc, wbc, folio, inode,
pos, rlen, &count);
if (error)
break;
pos += rlen;
}
if (count)
wpc->nr_folios++;
/*
* 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.
*/
folio_unlock(folio);
if (ifs) {
if (atomic_dec_and_test(&ifs->write_bytes_pending))
folio_end_writeback(folio);
} else {
if (!count)
folio_end_writeback(folio);
}
mapping_set_error(inode->i_mapping, error);
return error;
}
int
iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
struct iomap_writepage_ctx *wpc,
const struct iomap_writeback_ops *ops)
{
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;
wpc->ops = ops;
while ((folio = writeback_iter(mapping, wbc, folio, &error)))
error = iomap_writepage_map(wpc, wbc, folio);
return iomap_submit_ioend(wpc, error);
}
EXPORT_SYMBOL_GPL(iomap_writepages);
static int __init iomap_buffered_init(void)
{
return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
offsetof(struct iomap_ioend, io_bio),
BIOSET_NEED_BVECS);
}
fs_initcall(iomap_buffered_init);
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