// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2010 Red Hat, Inc.
* Copyright (C) 2016-2019 Christoph Hellwig.
*/
#include <linux/module.h>
#include <linux/compiler.h>
#include <linux/fs.h>
#include <linux/iomap.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/buffer_head.h>
#include <linux/dax.h>
#include <linux/writeback.h>
#include <linux/list_sort.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/sched/signal.h>
#include <linux/migrate.h>
#include "trace.h"
#include "../internal.h"
/*
* Structure allocated for each page or THP when block size < page size
* to track sub-page uptodate status and I/O completions.
*/
struct iomap_page {
atomic_t read_bytes_pending;
atomic_t write_bytes_pending;
spinlock_t uptodate_lock;
unsigned long uptodate[];
};
static inline struct iomap_page *to_iomap_page(struct page *page)
{
/*
* per-block data is stored in the head page. Callers should
* not be dealing with tail pages (and if they are, they can
* call thp_head() first.
*/
VM_BUG_ON_PGFLAGS(PageTail(page), page);
if (page_has_private(page))
return (struct iomap_page *)page_private(page);
return NULL;
}
static struct bio_set iomap_ioend_bioset;
static struct iomap_page *
iomap_page_create(struct inode *inode, struct page *page)
{
struct iomap_page *iop = to_iomap_page(page);
unsigned int nr_blocks = i_blocks_per_page(inode, page);
if (iop || nr_blocks <= 1)
return iop;
iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
GFP_NOFS | __GFP_NOFAIL);
spin_lock_init(&iop->uptodate_lock);
if (PageUptodate(page))
bitmap_fill(iop->uptodate, nr_blocks);
attach_page_private(page, iop);
return iop;
}
static void
iomap_page_release(struct page *page)
{
struct iomap_page *iop = detach_page_private(page);
unsigned int nr_blocks = i_blocks_per_page(page->mapping->host, page);
if (!iop)
return;
WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));
WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending));
WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=
PageUptodate(page));
kfree(iop);
}
/*
* Calculate the range inside the page that we actually need to read.
*/
static void
iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
{
loff_t orig_pos = *pos;
loff_t isize = i_size_read(inode);
unsigned block_bits = inode->i_blkbits;
unsigned block_size = (1 << block_bits);
unsigned poff = offset_in_page(*pos);
unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
unsigned first = poff >> block_bits;
unsigned last = (poff + plen - 1) >> block_bits;
/*
* If the block size is smaller than the page size we need to check the
* per-block uptodate status and adjust the offset and length if needed
* to avoid reading in already uptodate ranges.
*/
if (iop) {
unsigned int i;
/* move forward for each leading block marked uptodate */
for (i = first; i <= last; i++) {
if (!test_bit(i, iop->uptodate))
break;
*pos += block_size;
poff += block_size;
plen -= block_size;
first++;
}
/* truncate len if we find any trailing uptodate block(s) */
for ( ; i <= last; i++) {
if (test_bit(i, iop->uptodate)) {
plen -= (last - i + 1) * block_size;
last = i - 1;
break;
}
}
}
/*
* If the extent spans the block that contains the i_size we need to
* handle both halves separately so that we properly zero data in the
* page cache for blocks that are entirely outside of i_size.
*/
if (orig_pos <= isize && orig_pos + length > isize) {
unsigned end = offset_in_page(isize - 1) >> block_bits;
if (first <= end && last > end)
plen -= (last - end) * block_size;
}
*offp = poff;
*lenp = plen;
}
static void
iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
{
struct iomap_page *iop = to_iomap_page(page);
struct inode *inode = page->mapping->host;
unsigned first = off >> inode->i_blkbits;
unsigned last = (off + len - 1) >> inode->i_blkbits;
unsigned long flags;
spin_lock_irqsave(&iop->uptodate_lock, flags);
bitmap_set(iop->uptodate, first, last - first + 1);
if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page)))
SetPageUptodate(page);
spin_unlock_irqrestore(&iop->uptodate_lock, flags);
}
static void
iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
{
if (PageError(page))
return;
if (page_has_private(page))
iomap_iop_set_range_uptodate(page, off, len);
else
SetPageUptodate(page);
}
static void
iomap_read_page_end_io(struct bio_vec *bvec, int error)
{
struct page *page = bvec->bv_page;
struct iomap_page *iop = to_iomap_page(page);
if (unlikely(error)) {
ClearPageUptodate(page);
SetPageError(page);
} else {
iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
}
if (!iop || atomic_sub_and_test(bvec->bv_len, &iop->read_bytes_pending))
unlock_page(page);
}
static void
iomap_read_end_io(struct bio *bio)
{
int error = blk_status_to_errno(bio->bi_status);
struct bio_vec *bvec;
struct bvec_iter_all iter_all;
bio_for_each_segment_all(bvec, bio, iter_all)
iomap_read_page_end_io(bvec, error);
bio_put(bio);
}
struct iomap_readpage_ctx {
struct page *cur_page;
bool cur_page_in_bio;
struct bio *bio;
struct readahead_control *rac;
};
static void
iomap_read_inline_data(struct inode *inode, struct page *page,
struct iomap *iomap)
{
size_t size = i_size_read(inode);
void *addr;
if (PageUptodate(page))
return;
BUG_ON(page->index);
BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
addr = kmap_atomic(page);
memcpy(addr, iomap->inline_data, size);
memset(addr + size, 0, PAGE_SIZE - size);
kunmap_atomic(addr);
SetPageUptodate(page);
}
static inline bool iomap_block_needs_zeroing(struct inode *inode,
struct iomap *iomap, loff_t pos)
{
return iomap->type != IOMAP_MAPPED ||
(iomap->flags & IOMAP_F_NEW) ||
pos >= i_size_read(inode);
}
static loff_t
iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_readpage_ctx *ctx = data;
struct page *page = ctx->cur_page;
struct iomap_page *iop = iomap_page_create(inode, page);
bool same_page = false, is_contig = false;
loff_t orig_pos = pos;
unsigned poff, plen;
sector_t sector;
if (iomap->type == IOMAP_INLINE) {
WARN_ON_ONCE(pos);
iomap_read_inline_data(inode, page, iomap);
return PAGE_SIZE;
}
/* zero post-eof blocks as the page may be mapped */
iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
if (plen == 0)
goto done;
if (iomap_block_needs_zeroing(inode, iomap, pos)) {
zero_user(page, poff, plen);
iomap_set_range_uptodate(page, poff, plen);
goto done;
}
ctx->cur_page_in_bio = true;
if (iop)
atomic_add(plen, &iop->read_bytes_pending);
/* Try to merge into a previous segment if we can */
sector = iomap_sector(iomap, pos);
if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
if (__bio_try_merge_page(ctx->bio, page, plen, poff,
&same_page))
goto done;
is_contig = true;
}
if (!is_contig || bio_full(ctx->bio, plen)) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
gfp_t orig_gfp = gfp;
unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
if (ctx->bio)
submit_bio(ctx->bio);
if (ctx->rac) /* same as readahead_gfp_mask */
gfp |= __GFP_NORETRY | __GFP_NOWARN;
ctx->bio = bio_alloc(gfp, bio_max_segs(nr_vecs));
/*
* If the bio_alloc fails, try it again for a single page to
* avoid having to deal with partial page reads. This emulates
* what do_mpage_readpage does.
*/
if (!ctx->bio)
ctx->bio = bio_alloc(orig_gfp, 1);
ctx->bio->bi_opf = REQ_OP_READ;
if (ctx->rac)
ctx->bio->bi_opf |= REQ_RAHEAD;
ctx->bio->bi_iter.bi_sector = sector;
bio_set_dev(ctx->bio, iomap->bdev);
ctx->bio->bi_end_io = iomap_read_end_io;
}
bio_add_page(ctx->bio, page, plen, poff);
done:
/*
* Move the caller beyond our range so that it keeps making progress.
* For that we have to include any leading non-uptodate ranges, but
* we can skip trailing ones as they will be handled in the next
* iteration.
*/
return pos - orig_pos + plen;
}
int
iomap_readpage(struct page *page, const struct iomap_ops *ops)
{
struct iomap_readpage_ctx ctx = { .cur_page = page };
struct inode *inode = page->mapping->host;
unsigned poff;
loff_t ret;
trace_iomap_readpage(page->mapping->host, 1);
for (poff = 0; poff < PAGE_SIZE; poff += ret) {
ret = iomap_apply(inode, page_offset(page) + poff,
PAGE_SIZE - poff, 0, ops, &ctx,
iomap_readpage_actor);
if (ret <= 0) {
WARN_ON_ONCE(ret == 0);
SetPageError(page);
break;
}
}
if (ctx.bio) {
submit_bio(ctx.bio);
WARN_ON_ONCE(!ctx.cur_page_in_bio);
} else {
WARN_ON_ONCE(ctx.cur_page_in_bio);
unlock_page(page);
}
/*
* Just like mpage_readahead and block_read_full_page we always
* return 0 and just mark the page as PageError on errors. This
* should be cleaned up all through the stack eventually.
*/
return 0;
}
EXPORT_SYMBOL_GPL(iomap_readpage);
static loff_t
iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct iomap_readpage_ctx *ctx = data;
loff_t done, ret;
for (done = 0; done < length; done += ret) {
if (ctx->cur_page && offset_in_page(pos + done) == 0) {
if (!ctx->cur_page_in_bio)
unlock_page(ctx->cur_page);
put_page(ctx->cur_page);
ctx->cur_page = NULL;
}
if (!ctx->cur_page) {
ctx->cur_page = readahead_page(ctx->rac);
ctx->cur_page_in_bio = false;
}
ret = iomap_readpage_actor(inode, pos + done, length - done,
ctx, iomap, srcmap);
}
return done;
}
/**
* iomap_readahead - Attempt to read pages from a file.
* @rac: Describes the pages to be read.
* @ops: The operations vector for the filesystem.
*
* This function is for filesystems to call to implement their readahead
* address_space operation.
*
* Context: The @ops callbacks may submit I/O (eg to read the addresses of
* blocks from disc), and may wait for it. The caller may be trying to
* access a different page, and so sleeping excessively should be avoided.
* It may allocate memory, but should avoid costly allocations. This
* function is called with memalloc_nofs set, so allocations will not cause
* the filesystem to be reentered.
*/
void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
{
struct inode *inode = rac->mapping->host;
loff_t pos = readahead_pos(rac);
size_t length = readahead_length(rac);
struct iomap_readpage_ctx ctx = {
.rac = rac,
};
trace_iomap_readahead(inode, readahead_count(rac));
while (length > 0) {
ssize_t ret = iomap_apply(inode, pos, length, 0, ops,
&ctx, iomap_readahead_actor);
if (ret <= 0) {
WARN_ON_ONCE(ret == 0);
break;
}
pos += ret;
length -= ret;
}
if (ctx.bio)
submit_bio(ctx.bio);
if (ctx.cur_page) {
if (!ctx.cur_page_in_bio)
unlock_page(ctx.cur_page);
put_page(ctx.cur_page);
}
}
EXPORT_SYMBOL_GPL(iomap_readahead);
/*
* iomap_is_partially_uptodate checks whether blocks within a page are
* uptodate or not.
*
* Returns true if all blocks which correspond to a file portion
* we want to read within the page are uptodate.
*/
int
iomap_is_partially_uptodate(struct page *page, unsigned long from,
unsigned long count)
{
struct iomap_page *iop = to_iomap_page(page);
struct inode *inode = page->mapping->host;
unsigned len, first, last;
unsigned i;
/* Limit range to one page */
len = min_t(unsigned, PAGE_SIZE - from, count);
/* First and last blocks in range within page */
first = from >> inode->i_blkbits;
last = (from + len - 1) >> inode->i_blkbits;
if (iop) {
for (i = first; i <= last; i++)
if (!test_bit(i, iop->uptodate))
return 0;
return 1;
}
return 0;
}
EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
int
iomap_releasepage(struct page *page, gfp_t gfp_mask)
{
trace_iomap_releasepage(page->mapping->host, page_offset(page),
PAGE_SIZE);
/*
* mm accommodates an old ext3 case where clean pages might not have had
* the dirty bit cleared. Thus, it can send actual dirty pages to
* ->releasepage() via shrink_active_list(), skip those here.
*/
if (PageDirty(page) || PageWriteback(page))
return 0;
iomap_page_release(page);
return 1;
}
EXPORT_SYMBOL_GPL(iomap_releasepage);
void
iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
{
trace_iomap_invalidatepage(page->mapping->host, offset, len);
/*
* If we are invalidating the entire page, clear the dirty state from it
* and release it to avoid unnecessary buildup of the LRU.
*/
if (offset == 0 && len == PAGE_SIZE) {
WARN_ON_ONCE(PageWriteback(page));
cancel_dirty_page(page);
iomap_page_release(page);
}
}
EXPORT_SYMBOL_GPL(iomap_invalidatepage);
#ifdef CONFIG_MIGRATION
int
iomap_migrate_page(struct address_space *mapping, struct page *newpage,
struct page *page, enum migrate_mode mode)
{
int ret;
ret = migrate_page_move_mapping(mapping, newpage, page, 0);
if (ret != MIGRATEPAGE_SUCCESS)
return ret;
if (page_has_private(page))
attach_page_private(newpage, detach_page_private(page));
if (mode != MIGRATE_SYNC_NO_COPY)
migrate_page_copy(newpage, page);
else
migrate_page_states(newpage, page);
return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL_GPL(iomap_migrate_page);
#endif /* CONFIG_MIGRATION */
enum {
IOMAP_WRITE_F_UNSHARE = (1 << 0),
};
static void
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
{
loff_t i_size = i_size_read(inode);
/*
* Only truncate newly allocated pages beyoned EOF, even if the
* write started inside the existing inode size.
*/
if (pos + len > i_size)
truncate_pagecache_range(inode, max(pos, i_size), pos + len);
}
static int
iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff,
unsigned plen, struct iomap *iomap)
{
struct bio_vec bvec;
struct bio bio;
bio_init(&bio, &bvec, 1);
bio.bi_opf = REQ_OP_READ;
bio.bi_iter.bi_sector = iomap_sector(iomap, block_start);
bio_set_dev(&bio, iomap->bdev);
__bio_add_page(&bio, page, plen, poff);
return submit_bio_wait(&bio);
}
static int
__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
struct page *page, struct iomap *srcmap)
{
struct iomap_page *iop = iomap_page_create(inode, page);
loff_t block_size = i_blocksize(inode);
loff_t block_start = round_down(pos, block_size);
loff_t block_end = round_up(pos + len, block_size);
unsigned from = offset_in_page(pos), to = from + len, poff, plen;
if (PageUptodate(page))
return 0;
ClearPageError(page);
do {
iomap_adjust_read_range(inode, iop, &block_start,
block_end - block_start, &poff, &plen);
if (plen == 0)
break;
if (!(flags & IOMAP_WRITE_F_UNSHARE) &&
(from <= poff || from >= poff + plen) &&
(to <= poff || to >= poff + plen))
continue;
if (iomap_block_needs_zeroing(inode, srcmap, block_start)) {
if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
return -EIO;
zero_user_segments(page, poff, from, to, poff + plen);
} else {
int status = iomap_read_page_sync(block_start, page,
poff, plen, srcmap);
if (status)
return status;
}
iomap_set_range_uptodate(page, poff, plen);
} while ((block_start += plen) < block_end);
return 0;
}
static int
iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
struct page **pagep, struct iomap *iomap, struct iomap *srcmap)
{
const struct iomap_page_ops *page_ops = iomap->page_ops;
struct page *page;
int status = 0;
BUG_ON(pos + len > iomap->offset + iomap->length);
if (srcmap != iomap)
BUG_ON(pos + len > srcmap->offset + srcmap->length);
if (fatal_signal_pending(current))
return -EINTR;
if (page_ops && page_ops->page_prepare) {
status = page_ops->page_prepare(inode, pos, len, iomap);
if (status)
return status;
}
page = grab_cache_page_write_begin(inode->i_mapping, pos >> PAGE_SHIFT,
AOP_FLAG_NOFS);
if (!page) {
status = -ENOMEM;
goto out_no_page;
}
if (srcmap->type == IOMAP_INLINE)
iomap_read_inline_data(inode, page, srcmap);
else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
status = __block_write_begin_int(page, pos, len, NULL, srcmap);
else
status = __iomap_write_begin(inode, pos, len, flags, page,
srcmap);
if (unlikely(status))
goto out_unlock;
*pagep = page;
return 0;
out_unlock:
unlock_page(page);
put_page(page);
iomap_write_failed(inode, pos, len);
out_no_page:
if (page_ops && page_ops->page_done)
page_ops->page_done(inode, pos, 0, NULL, iomap);
return status;
}
int
iomap_set_page_dirty(struct page *page)
{
struct address_space *mapping = page_mapping(page);
int newly_dirty;
if (unlikely(!mapping))
return !TestSetPageDirty(page);
/*
* Lock out page's memcg migration to keep PageDirty
* synchronized with per-memcg dirty page counters.
*/
lock_page_memcg(page);
newly_dirty = !TestSetPageDirty(page);
if (newly_dirty)
__set_page_dirty(page, mapping, 0);
unlock_page_memcg(page);
if (newly_dirty)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
return newly_dirty;
}
EXPORT_SYMBOL_GPL(iomap_set_page_dirty);
static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
size_t copied, struct page *page)
{
flush_dcache_page(page);
/*
* The blocks that were entirely written will now be uptodate, so we
* don't have to worry about a readpage reading them and overwriting a
* partial write. However if we have encountered a short write and only
* partially written into a block, it will not be marked uptodate, so a
* readpage might come in and destroy our partial write.
*
* Do the simplest thing, and just treat any short write to a non
* uptodate page as a zero-length write, and force the caller to redo
* the whole thing.
*/
if (unlikely(copied < len && !PageUptodate(page)))
return 0;
iomap_set_range_uptodate(page, offset_in_page(pos), len);
iomap_set_page_dirty(page);
return copied;
}
static size_t iomap_write_end_inline(struct inode *inode, struct page *page,
struct iomap *iomap, loff_t pos, size_t copied)
{
void *addr;
WARN_ON_ONCE(!PageUptodate(page));
BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
flush_dcache_page(page);
addr = kmap_atomic(page);
memcpy(iomap->inline_data + pos, addr + pos, copied);
kunmap_atomic(addr);
mark_inode_dirty(inode);
return copied;
}
/* Returns the number of bytes copied. May be 0. Cannot be an errno. */
static size_t iomap_write_end(struct inode *inode, loff_t pos, size_t len,
size_t copied, struct page *page, struct iomap *iomap,
struct iomap *srcmap)
{
const struct iomap_page_ops *page_ops = iomap->page_ops;
loff_t old_size = inode->i_size;
size_t ret;
if (srcmap->type == IOMAP_INLINE) {
ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
} else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
page, NULL);
} else {
ret = __iomap_write_end(inode, pos, len, copied, page);
}
/*
* Update the in-memory inode size after copying the data into the page
* cache. It's up to the file system to write the updated size to disk,
* preferably after I/O completion so that no stale data is exposed.
*/
if (pos + ret > old_size) {
i_size_write(inode, pos + ret);
iomap->flags |= IOMAP_F_SIZE_CHANGED;
}
unlock_page(page);
if (old_size < pos)
pagecache_isize_extended(inode, old_size, pos);
if (page_ops && page_ops->page_done)
page_ops->page_done(inode, pos, ret, page, iomap);
put_page(page);
if (ret < len)
iomap_write_failed(inode, pos, len);
return ret;
}
static loff_t
iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap, struct iomap *srcmap)
{
struct iov_iter *i = data;
long status = 0;
ssize_t written = 0;
do {
struct page *page;
unsigned long offset; /* Offset into pagecache page */
unsigned long bytes; /* Bytes to write to page */
size_t copied; /* Bytes copied from user */
offset = offset_in_page(pos);
bytes = min_t(unsigned long, PAGE_SIZE - offset,
iov_iter_count(i));
again:
if (bytes > length)
bytes = length;
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
* same page as we're writing to, without it being marked
* up-to-date.
*
* Not only is this an optimisation, but it is also required
* to check that the address is actually valid, when atomic
* usercopies are used, below.
*/
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
status = -EFAULT;
break;
}
status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap,
srcmap);
if (unlikely(status))
break;
if (mapping_writably_mapped(inode->i_mapping))
flush_dcache_page(page);
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
copied = iomap_write_end(inode, pos, bytes, copied, page, iomap,
srcmap);
cond_resched();
iov_iter_advance(i, copied);
if (unlikely(copied == 0)) {
/*
* If we were unable to copy any data at all, we must
* fall back to a single segment length write.
*
* If we didn't fallback here, we could livelock
* because not all segments in the iov can be copied at
* once without a pagefault.
*/
bytes = min_t(unsigned long, PAGE_SIZE - offset,
iov_iter_single_seg_count(i));
goto again;
}
pos += copied;
written += copied;
length -= copied;
balance_dirty_pages_ratelimited(inode->i_mapping);
} while (iov_iter_count(i) && length);
return written ? written : status;
}
ssize_t
iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
loff_t pos = iocb->ki_pos, ret = 0, written = 0;
while (iov_iter_count(iter)) {
ret = iomap_apply(inode, pos, iov_iter_count(iter),
IOMAP_WRITE, ops, iter, iomap_write_actor);
if (ret <= 0)
break;
pos += ret;
written += ret;
}
return written ? written : ret;
}
EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
static loff_t
iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap, struct iomap *srcmap)
{
long status = 0;
loff_t written = 0;
/* don't bother with blocks that are not shared to start with */
if (!(iomap->flags & IOMAP_F_SHARED))
return length;
/* don't bother with holes or unwritten extents */
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
return length;
do {
unsigned long offset = offset_in_page(pos);
unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
struct page *page;
status = iomap_write_begin(inode, pos, bytes,
IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap);
if (unlikely(status))
return status;
status = iomap_write_end(inode, pos, bytes, bytes, page, iomap,
srcmap);
if (WARN_ON_ONCE(status == 0))
return -EIO;
cond_resched();
pos += status;
written += status;
length -= status;
balance_dirty_pages_ratelimited(inode->i_mapping);
} while (length);
return written;
}
int
iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
const struct iomap_ops *ops)
{
loff_t ret;
while (len) {
ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
iomap_unshare_actor);
if (ret <= 0)
return ret;
pos += ret;
len -= ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(iomap_file_unshare);
static s64 iomap_zero(struct inode *inode, loff_t pos, u64 length,
struct iomap *iomap, struct iomap *srcmap)
{
struct page *page;
int status;
unsigned offset = offset_in_page(pos);
unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);
status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap);
if (status)
return status;
zero_user(page, offset, bytes);
mark_page_accessed(page);
return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap);
}
static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos,
loff_t length, void *data, struct iomap *iomap,
struct iomap *srcmap)
{
bool *did_zero = data;
loff_t written = 0;
/* already zeroed? we're done. */
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
return length;
do {
s64 bytes;
if (IS_DAX(inode))
bytes = dax_iomap_zero(pos, length, iomap);
else
bytes = iomap_zero(inode, pos, length, iomap, srcmap);
if (bytes < 0)
return bytes;
pos += bytes;
length -= bytes;
written += bytes;
if (did_zero)
*did_zero = true;
} while (length > 0);
return written;
}
int
iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
const struct iomap_ops *ops)
{
loff_t ret;
while (len > 0) {
ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
ops, did_zero, iomap_zero_range_actor);
if (ret <= 0)
return ret;
pos += ret;
len -= ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(iomap_zero_range);
int
iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
const struct iomap_ops *ops)
{
unsigned int blocksize = i_blocksize(inode);
unsigned int off = pos & (blocksize - 1);
/* Block boundary? Nothing to do */
if (!off)
return 0;
return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
}
EXPORT_SYMBOL_GPL(iomap_truncate_page);
static loff_t
iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap, struct iomap *srcmap)
{
struct page *page = data;
int ret;
if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
ret = __block_write_begin_int(page, pos, length, NULL, iomap);
if (ret)
return ret;
block_commit_write(page, 0, length);
} else {
WARN_ON_ONCE(!PageUptodate(page));
iomap_page_create(inode, page);
set_page_dirty(page);
}
return length;
}
vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
{
struct page *page = vmf->page;
struct inode *inode = file_inode(vmf->vma->vm_file);
unsigned long length;
loff_t offset;
ssize_t ret;
lock_page(page);
ret = page_mkwrite_check_truncate(page, inode);
if (ret < 0)
goto out_unlock;
length = ret;
offset = page_offset(page);
while (length > 0) {
ret = iomap_apply(inode, offset, length,
IOMAP_WRITE | IOMAP_FAULT, ops, page,
iomap_page_mkwrite_actor);
if (unlikely(ret <= 0))
goto out_unlock;
offset += ret;
length -= ret;
}
wait_for_stable_page(page);
return VM_FAULT_LOCKED;
out_unlock:
unlock_page(page);
return block_page_mkwrite_return(ret);
}
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
static void
iomap_finish_page_writeback(struct inode *inode, struct page *page,
int error, unsigned int len)
{
struct iomap_page *iop = to_iomap_page(page);
if (error) {
SetPageError(page);
mapping_set_error(inode->i_mapping, -EIO);
}
WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop);
WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) <= 0);
if (!iop || atomic_sub_and_test(len, &iop->write_bytes_pending))
end_page_writeback(page);
}
/*
* We're now finished for good with this ioend structure. Update the page
* state, release holds on bios, and finally free up memory. Do not use the
* ioend after this.
*/
static void
iomap_finish_ioend(struct iomap_ioend *ioend, int error)
{
struct inode *inode = ioend->io_inode;
struct bio *bio = &ioend->io_inline_bio;
struct bio *last = ioend->io_bio, *next;
u64 start = bio->bi_iter.bi_sector;
loff_t offset = ioend->io_offset;
bool quiet = bio_flagged(bio, BIO_QUIET);
for (bio = &ioend->io_inline_bio; bio; bio = next) {
struct bio_vec *bv;
struct bvec_iter_all iter_all;
/*
* For the last bio, bi_private points to the ioend, so we
* need to explicitly end the iteration here.
*/
if (bio == last)
next = NULL;
else
next = bio->bi_private;
/* walk each page on bio, ending page IO on them */
bio_for_each_segment_all(bv, bio, iter_all)
iomap_finish_page_writeback(inode, bv->bv_page, error,
bv->bv_len);
bio_put(bio);
}
/* The ioend has been freed by bio_put() */
if (unlikely(error && !quiet)) {
printk_ratelimited(KERN_ERR
"%s: writeback error on inode %lu, offset %lld, sector %llu",
inode->i_sb->s_id, inode->i_ino, offset, start);
}
}
void
iomap_finish_ioends(struct iomap_ioend *ioend, int error)
{
struct list_head tmp;
list_replace_init(&ioend->io_list, &tmp);
iomap_finish_ioend(ioend, error);
while (!list_empty(&tmp)) {
ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
list_del_init(&ioend->io_list);
iomap_finish_ioend(ioend, error);
}
}
EXPORT_SYMBOL_GPL(iomap_finish_ioends);
/*
* We can merge two adjacent ioends if they have the same set of work to do.
*/
static bool
iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
{
if (ioend->io_bio->bi_status != next->io_bio->bi_status)
return false;
if ((ioend->io_flags & IOMAP_F_SHARED) ^
(next->io_flags & IOMAP_F_SHARED))
return false;
if ((ioend->io_type == IOMAP_UNWRITTEN) ^
(next->io_type == IOMAP_UNWRITTEN))
return false;
if (ioend->io_offset + ioend->io_size != next->io_offset)
return false;
return true;
}
void
iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends)
{
struct iomap_ioend *next;
INIT_LIST_HEAD(&ioend->io_list);
while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend,
io_list))) {
if (!iomap_ioend_can_merge(ioend, next))
break;
list_move_tail(&next->io_list, &ioend->io_list);
ioend->io_size += next->io_size;
}
}
EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
static int
iomap_ioend_compare(void *priv, const struct list_head *a,
const struct list_head *b)
{
struct iomap_ioend *ia = container_of(a, struct iomap_ioend, io_list);
struct iomap_ioend *ib = container_of(b, struct iomap_ioend, io_list);
if (ia->io_offset < ib->io_offset)
return -1;
if (ia->io_offset > ib->io_offset)
return 1;
return 0;
}
void
iomap_sort_ioends(struct list_head *ioend_list)
{
list_sort(NULL, ioend_list, iomap_ioend_compare);
}
EXPORT_SYMBOL_GPL(iomap_sort_ioends);
static void iomap_writepage_end_bio(struct bio *bio)
{
struct iomap_ioend *ioend = bio->bi_private;
iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status));
}
/*
* Submit the final bio for an ioend.
*
* If @error is non-zero, it means that we have a situation where some part of
* the submission process has failed after we have marked paged for writeback
* and unlocked them. In this situation, we need to fail the bio instead of
* submitting it. This typically only happens on a filesystem shutdown.
*/
static int
iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend,
int error)
{
ioend->io_bio->bi_private = ioend;
ioend->io_bio->bi_end_io = iomap_writepage_end_bio;
if (wpc->ops->prepare_ioend)
error = wpc->ops->prepare_ioend(ioend, error);
if (error) {
/*
* If we are failing the IO now, just mark the ioend with an
* error and finish it. This will run IO completion immediately
* as there is only one reference to the ioend at this point in
* time.
*/
ioend->io_bio->bi_status = errno_to_blk_status(error);
bio_endio(ioend->io_bio);
return error;
}
submit_bio(ioend->io_bio);
return 0;
}
static struct iomap_ioend *
iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
loff_t offset, sector_t sector, struct writeback_control *wbc)
{
struct iomap_ioend *ioend;
struct bio *bio;
bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_VECS, &iomap_ioend_bioset);
bio_set_dev(bio, wpc->iomap.bdev);
bio->bi_iter.bi_sector = sector;
bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
bio->bi_write_hint = inode->i_write_hint;
wbc_init_bio(wbc, bio);
ioend = container_of(bio, struct iomap_ioend, io_inline_bio);
INIT_LIST_HEAD(&ioend->io_list);
ioend->io_type = wpc->iomap.type;
ioend->io_flags = wpc->iomap.flags;
ioend->io_inode = inode;
ioend->io_size = 0;
ioend->io_offset = offset;
ioend->io_bio = bio;
return ioend;
}
/*
* Allocate a new bio, and chain the old bio to the new one.
*
* Note that we have to do perform the chaining in this unintuitive order
* so that the bi_private linkage is set up in the right direction for the
* traversal in iomap_finish_ioend().
*/
static struct bio *
iomap_chain_bio(struct bio *prev)
{
struct bio *new;
new = bio_alloc(GFP_NOFS, BIO_MAX_VECS);
bio_copy_dev(new, prev);/* also copies over blkcg information */
new->bi_iter.bi_sector = bio_end_sector(prev);
new->bi_opf = prev->bi_opf;
new->bi_write_hint = prev->bi_write_hint;
bio_chain(prev, new);
bio_get(prev); /* for iomap_finish_ioend */
submit_bio(prev);
return new;
}
static bool
iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t offset,
sector_t sector)
{
if ((wpc->iomap.flags & IOMAP_F_SHARED) !=
(wpc->ioend->io_flags & IOMAP_F_SHARED))
return false;
if (wpc->iomap.type != wpc->ioend->io_type)
return false;
if (offset != wpc->ioend->io_offset + wpc->ioend->io_size)
return false;
if (sector != bio_end_sector(wpc->ioend->io_bio))
return false;
return true;
}
/*
* Test to see if we have an existing ioend structure that we could append to
* first, otherwise finish off the current ioend and start another.
*/
static void
iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
struct iomap_page *iop, struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct list_head *iolist)
{
sector_t sector = iomap_sector(&wpc->iomap, offset);
unsigned len = i_blocksize(inode);
unsigned poff = offset & (PAGE_SIZE - 1);
bool merged, same_page = false;
if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) {
if (wpc->ioend)
list_add(&wpc->ioend->io_list, iolist);
wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc);
}
merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
&same_page);
if (iop)
atomic_add(len, &iop->write_bytes_pending);
if (!merged) {
if (bio_full(wpc->ioend->io_bio, len)) {
wpc->ioend->io_bio =
iomap_chain_bio(wpc->ioend->io_bio);
}
bio_add_page(wpc->ioend->io_bio, page, len, poff);
}
wpc->ioend->io_size += len;
wbc_account_cgroup_owner(wbc, page, len);
}
/*
* We implement an immediate ioend submission policy here to avoid needing to
* chain multiple ioends and hence nest mempool allocations which can violate
* forward progress guarantees we need to provide. The current ioend we are
* adding blocks to is cached on the writepage context, and if the new block
* does not append to the cached ioend it will create a new ioend and cache that
* instead.
*
* If a new ioend is created and cached, the old ioend is returned and queued
* locally for submission once the entire page is processed or an error has been
* detected. While ioends are submitted immediately after they are completed,
* batching optimisations are provided by higher level block plugging.
*
* At the end of a writeback pass, there will be a cached ioend remaining on the
* writepage context that the caller will need to submit.
*/
static int
iomap_writepage_map(struct iomap_writepage_ctx *wpc,
struct writeback_control *wbc, struct inode *inode,
struct page *page, u64 end_offset)
{
struct iomap_page *iop = to_iomap_page(page);
struct iomap_ioend *ioend, *next;
unsigned len = i_blocksize(inode);
u64 file_offset; /* file offset of page */
int error = 0, count = 0, i;
LIST_HEAD(submit_list);
WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop);
WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
/*
* Walk through the page to find areas to write back. If we run off the
* end of the current map or find the current map invalid, grab a new
* one.
*/
for (i = 0, file_offset = page_offset(page);
i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
i++, file_offset += len) {
if (iop && !test_bit(i, iop->uptodate))
continue;
error = wpc->ops->map_blocks(wpc, inode, file_offset);
if (error)
break;
if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE))
continue;
if (wpc->iomap.type == IOMAP_HOLE)
continue;
iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
&submit_list);
count++;
}
WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list));
WARN_ON_ONCE(!PageLocked(page));
WARN_ON_ONCE(PageWriteback(page));
WARN_ON_ONCE(PageDirty(page));
/*
* We cannot cancel the ioend directly here on error. We may have
* already set other pages under writeback and hence we have to run I/O
* completion to mark the error state of the pages under writeback
* appropriately.
*/
if (unlikely(error)) {
/*
* Let the filesystem know what portion of the current page
* failed to map. If the page wasn't been added to ioend, it
* won't be affected by I/O completion and we must unlock it
* now.
*/
if (wpc->ops->discard_page)
wpc->ops->discard_page(page, file_offset);
if (!count) {
ClearPageUptodate(page);
unlock_page(page);
goto done;
}
}
set_page_writeback(page);
unlock_page(page);
/*
* Preserve the original error if there was one, otherwise catch
* submission errors here and propagate into subsequent ioend
* submissions.
*/
list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
int error2;
list_del_init(&ioend->io_list);
error2 = iomap_submit_ioend(wpc, ioend, error);
if (error2 && !error)
error = error2;
}
/*
* We can end up here with no error and nothing to write only if we race
* with a partial page truncate on a sub-page block sized filesystem.
*/
if (!count)
end_page_writeback(page);
done:
mapping_set_error(page->mapping, error);
return error;
}
/*
* Write out a dirty page.
*
* For delalloc space on the page we need to allocate space and flush it.
* For unwritten space on the page we need to start the conversion to
* regular allocated space.
*/
static int
iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
{
struct iomap_writepage_ctx *wpc = data;
struct inode *inode = page->mapping->host;
pgoff_t end_index;
u64 end_offset;
loff_t offset;
trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE);
/*
* Refuse to write the page out if we are called from reclaim context.
*
* This avoids stack overflows when called from deeply used stacks in
* random callers for direct reclaim or memcg reclaim. We explicitly
* allow reclaim from kswapd as the stack usage there is relatively low.
*
* This should never happen except in the case of a VM regression so
* warn about it.
*/
if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
PF_MEMALLOC))
goto redirty;
/*
* Is this page beyond the end of the file?
*
* The page index is less than the end_index, adjust the end_offset
* to the highest offset that this page should represent.
* -----------------------------------------------------
* | file mapping | <EOF> |
* -----------------------------------------------------
* | Page ... | Page N-2 | Page N-1 | Page N | |
* ^--------------------------------^----------|--------
* | desired writeback range | see else |
* ---------------------------------^------------------|
*/
offset = i_size_read(inode);
end_index = offset >> PAGE_SHIFT;
if (page->index < end_index)
end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT;
else {
/*
* Check whether the page to write out is beyond or straddles
* i_size or not.
* -------------------------------------------------------
* | file mapping | <EOF> |
* -------------------------------------------------------
* | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
* ^--------------------------------^-----------|---------
* | | Straddles |
* ---------------------------------^-----------|--------|
*/
unsigned offset_into_page = offset & (PAGE_SIZE - 1);
/*
* Skip the page if it is fully outside i_size, e.g. due to a
* truncate operation that is in progress. We must redirty the
* page so that reclaim stops reclaiming it. Otherwise
* iomap_vm_releasepage() is called on it and gets confused.
*
* Note that the end_index is unsigned long, it would overflow
* if the given offset is greater than 16TB on 32-bit system
* and if we do check the page is fully outside i_size or not
* via "if (page->index >= end_index + 1)" as "end_index + 1"
* will be evaluated to 0. Hence this page will be redirtied
* and be written out repeatedly which would result in an
* infinite loop, the user program that perform this operation
* will hang. Instead, we can verify this situation by checking
* if the page to write is totally beyond the i_size or if it's
* offset is just equal to the EOF.
*/
if (page->index > end_index ||
(page->index == end_index && offset_into_page == 0))
goto redirty;
/*
* The page straddles i_size. It must be zeroed out on each
* and every writepage invocation because it may be mmapped.
* "A file is mapped in multiples of the page size. For a file
* that is not a multiple of the page size, the remaining
* memory is zeroed when mapped, and writes to that region are
* not written out to the file."
*/
zero_user_segment(page, offset_into_page, PAGE_SIZE);
/* Adjust the end_offset to the end of file */
end_offset = offset;
}
return iomap_writepage_map(wpc, wbc, inode, page, end_offset);
redirty:
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
int
iomap_writepage(struct page *page, struct writeback_control *wbc,
struct iomap_writepage_ctx *wpc,
const struct iomap_writeback_ops *ops)
{
int ret;
wpc->ops = ops;
ret = iomap_do_writepage(page, wbc, wpc);
if (!wpc->ioend)
return ret;
return iomap_submit_ioend(wpc, wpc->ioend, ret);
}
EXPORT_SYMBOL_GPL(iomap_writepage);
int
iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
struct iomap_writepage_ctx *wpc,
const struct iomap_writeback_ops *ops)
{
int ret;
wpc->ops = ops;
ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc);
if (!wpc->ioend)
return ret;
return iomap_submit_ioend(wpc, wpc->ioend, ret);
}
EXPORT_SYMBOL_GPL(iomap_writepages);
static int __init iomap_init(void)
{
return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
offsetof(struct iomap_ioend, io_inline_bio),
BIOSET_NEED_BVECS);
}
fs_initcall(iomap_init);
VisionFive2 Linux kernel
StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)
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