linux/fs/iomap.c
Piotr Jaroszynski 61c6de6672 fs/iomap.c: get/put the page in iomap_page_create/release()
migrate_page_move_mapping() expects pages with private data set to have
a page_count elevated by 1.  This is what used to happen for xfs through
the buffer_heads code before the switch to iomap in commit 82cb14175e
("xfs: add support for sub-pagesize writeback without buffer_heads").
Not having the count elevated causes move_pages() to fail on memory
mapped files coming from xfs.

Make iomap compatible with the migrate_page_move_mapping() assumption by
elevating the page count as part of iomap_page_create() and lowering it
in iomap_page_release().

It causes the move_pages() syscall to misbehave on memory mapped files
from xfs.  It does not not move any pages, which I suppose is "just" a
perf issue, but it also ends up returning a positive number which is out
of spec for the syscall.  Talking to Michal Hocko, it sounds like
returning positive numbers might be a necessary update to move_pages()
anyway though
(https://lkml.kernel.org/r/20181116114955.GJ14706@dhcp22.suse.cz).

I only hit this in tests that verify that move_pages() actually moved
the pages.  The test also got confused by the positive return from
move_pages() (it got treated as a success as positive numbers were not
expected and not handled) making it a bit harder to track down what's
going on.

Link: http://lkml.kernel.org/r/20181115184140.1388751-1-pjaroszynski@nvidia.com
Fixes: 82cb14175e ("xfs: add support for sub-pagesize writeback without buffer_heads")
Signed-off-by: Piotr Jaroszynski <pjaroszynski@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-14 15:05:45 -08:00

2137 lines
53 KiB
C

/*
* Copyright (C) 2010 Red Hat, Inc.
* Copyright (c) 2016-2018 Christoph Hellwig.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/module.h>
#include <linux/compiler.h>
#include <linux/fs.h>
#include <linux/iomap.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
#include <linux/migrate.h>
#include <linux/mm.h>
#include <linux/mm_inline.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/backing-dev.h>
#include <linux/buffer_head.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/dax.h>
#include <linux/sched/signal.h>
#include "internal.h"
/*
* Execute a iomap write on a segment of the mapping that spans a
* contiguous range of pages that have identical block mapping state.
*
* This avoids the need to map pages individually, do individual allocations
* for each page and most importantly avoid the need for filesystem specific
* locking per page. Instead, all the operations are amortised over the entire
* range of pages. It is assumed that the filesystems will lock whatever
* resources they require in the iomap_begin call, and release them in the
* iomap_end call.
*/
loff_t
iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
const struct iomap_ops *ops, void *data, iomap_actor_t actor)
{
struct iomap iomap = { 0 };
loff_t written = 0, ret;
/*
* Need to map a range from start position for length bytes. This can
* span multiple pages - it is only guaranteed to return a range of a
* single type of pages (e.g. all into a hole, all mapped or all
* unwritten). Failure at this point has nothing to undo.
*
* If allocation is required for this range, reserve the space now so
* that the allocation is guaranteed to succeed later on. Once we copy
* the data into the page cache pages, then we cannot fail otherwise we
* expose transient stale data. If the reserve fails, we can safely
* back out at this point as there is nothing to undo.
*/
ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
if (ret)
return ret;
if (WARN_ON(iomap.offset > pos))
return -EIO;
if (WARN_ON(iomap.length == 0))
return -EIO;
/*
* Cut down the length to the one actually provided by the filesystem,
* as it might not be able to give us the whole size that we requested.
*/
if (iomap.offset + iomap.length < pos + length)
length = iomap.offset + iomap.length - pos;
/*
* Now that we have guaranteed that the space allocation will succeed.
* we can do the copy-in page by page without having to worry about
* failures exposing transient data.
*/
written = actor(inode, pos, length, data, &iomap);
/*
* Now the data has been copied, commit the range we've copied. This
* should not fail unless the filesystem has had a fatal error.
*/
if (ops->iomap_end) {
ret = ops->iomap_end(inode, pos, length,
written > 0 ? written : 0,
flags, &iomap);
}
return written ? written : ret;
}
static sector_t
iomap_sector(struct iomap *iomap, loff_t pos)
{
return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
}
static struct iomap_page *
iomap_page_create(struct inode *inode, struct page *page)
{
struct iomap_page *iop = to_iomap_page(page);
if (iop || i_blocksize(inode) == PAGE_SIZE)
return iop;
iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
atomic_set(&iop->read_count, 0);
atomic_set(&iop->write_count, 0);
bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
/*
* migrate_page_move_mapping() assumes that pages with private data have
* their count elevated by 1.
*/
get_page(page);
set_page_private(page, (unsigned long)iop);
SetPagePrivate(page);
return iop;
}
static void
iomap_page_release(struct page *page)
{
struct iomap_page *iop = to_iomap_page(page);
if (!iop)
return;
WARN_ON_ONCE(atomic_read(&iop->read_count));
WARN_ON_ONCE(atomic_read(&iop->write_count));
ClearPagePrivate(page);
set_page_private(page, 0);
put_page(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_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 int i;
bool uptodate = true;
if (iop) {
for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
if (i >= first && i <= last)
set_bit(i, iop->uptodate);
else if (!test_bit(i, iop->uptodate))
uptodate = false;
}
}
if (uptodate && !PageError(page))
SetPageUptodate(page);
}
static void
iomap_read_finish(struct iomap_page *iop, struct page *page)
{
if (!iop || atomic_dec_and_test(&iop->read_count))
unlock_page(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);
}
iomap_read_finish(iop, page);
}
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 void
iomap_read_end_io(struct bio *bio)
{
int error = blk_status_to_errno(bio->bi_status);
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i)
iomap_read_page_end_io(bvec, error);
bio_put(bio);
}
struct iomap_readpage_ctx {
struct page *cur_page;
bool cur_page_in_bio;
bool is_readahead;
struct bio *bio;
struct list_head *pages;
};
static loff_t
iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
{
struct iomap_readpage_ctx *ctx = data;
struct page *page = ctx->cur_page;
struct iomap_page *iop = iomap_page_create(inode, page);
bool 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->type != IOMAP_MAPPED || pos >= i_size_read(inode)) {
zero_user(page, poff, plen);
iomap_set_range_uptodate(page, poff, plen);
goto done;
}
ctx->cur_page_in_bio = true;
/*
* 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))
goto done;
is_contig = true;
}
/*
* If we start a new segment we need to increase the read count, and we
* need to do so before submitting any previous full bio to make sure
* that we don't prematurely unlock the page.
*/
if (iop)
atomic_inc(&iop->read_count);
if (!ctx->bio || !is_contig || bio_full(ctx->bio)) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (ctx->bio)
submit_bio(ctx->bio);
if (ctx->is_readahead) /* same as readahead_gfp_mask */
gfp |= __GFP_NORETRY | __GFP_NOWARN;
ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
ctx->bio->bi_opf = REQ_OP_READ;
if (ctx->is_readahead)
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;
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_readpages 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 struct page *
iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos,
loff_t length, loff_t *done)
{
while (!list_empty(pages)) {
struct page *page = lru_to_page(pages);
if (page_offset(page) >= (u64)pos + length)
break;
list_del(&page->lru);
if (!add_to_page_cache_lru(page, inode->i_mapping, page->index,
GFP_NOFS))
return page;
/*
* If we already have a page in the page cache at index we are
* done. Upper layers don't care if it is uptodate after the
* readpages call itself as every page gets checked again once
* actually needed.
*/
*done += PAGE_SIZE;
put_page(page);
}
return NULL;
}
static loff_t
iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap)
{
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 = iomap_next_page(inode, ctx->pages,
pos, length, &done);
if (!ctx->cur_page)
break;
ctx->cur_page_in_bio = false;
}
ret = iomap_readpage_actor(inode, pos + done, length - done,
ctx, iomap);
}
return done;
}
int
iomap_readpages(struct address_space *mapping, struct list_head *pages,
unsigned nr_pages, const struct iomap_ops *ops)
{
struct iomap_readpage_ctx ctx = {
.pages = pages,
.is_readahead = true,
};
loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
loff_t last = page_offset(list_entry(pages->next, struct page, lru));
loff_t length = last - pos + PAGE_SIZE, ret = 0;
while (length > 0) {
ret = iomap_apply(mapping->host, pos, length, 0, ops,
&ctx, iomap_readpages_actor);
if (ret <= 0) {
WARN_ON_ONCE(ret == 0);
goto done;
}
pos += ret;
length -= ret;
}
ret = 0;
done:
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);
}
/*
* Check that we didn't lose a page due to the arcance calling
* conventions..
*/
WARN_ON_ONCE(!ret && !list_empty(ctx.pages));
return ret;
}
EXPORT_SYMBOL_GPL(iomap_readpages);
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 first = from >> inode->i_blkbits;
unsigned last = (from + count - 1) >> inode->i_blkbits;
unsigned i;
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)
{
/*
* 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)
{
/*
* 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, NULL, mode, 0);
if (ret != MIGRATEPAGE_SUCCESS)
return ret;
if (page_has_private(page)) {
ClearPagePrivate(page);
set_page_private(newpage, page_private(page));
set_page_private(page, 0);
SetPagePrivate(newpage);
}
if (mode != MIGRATE_SYNC_NO_COPY)
migrate_page_copy(newpage, page);
else
migrate_page_states(newpage, page);
return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL_GPL(iomap_migrate_page);
#endif /* CONFIG_MIGRATION */
static void
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
{
loff_t i_size = i_size_read(inode);
/*
* Only truncate newly allocated pages beyoned EOF, even if the
* write started inside the existing inode size.
*/
if (pos + len > i_size)
truncate_pagecache_range(inode, max(pos, i_size), pos + len);
}
static int
iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page,
unsigned poff, unsigned plen, unsigned from, unsigned to,
struct iomap *iomap)
{
struct bio_vec bvec;
struct bio bio;
if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) {
zero_user_segments(page, poff, from, to, poff + plen);
iomap_set_range_uptodate(page, poff, plen);
return 0;
}
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,
struct page *page, struct iomap *iomap)
{
struct iomap_page *iop = iomap_page_create(inode, page);
loff_t block_size = i_blocksize(inode);
loff_t block_start = pos & ~(block_size - 1);
loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
unsigned from = offset_in_page(pos), to = from + len, poff, plen;
int status = 0;
if (PageUptodate(page))
return 0;
do {
iomap_adjust_read_range(inode, iop, &block_start,
block_end - block_start, &poff, &plen);
if (plen == 0)
break;
if ((from > poff && from < poff + plen) ||
(to > poff && to < poff + plen)) {
status = iomap_read_page_sync(inode, block_start, page,
poff, plen, from, to, iomap);
if (status)
break;
}
} while ((block_start += plen) < block_end);
return status;
}
static int
iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
struct page **pagep, struct iomap *iomap)
{
pgoff_t index = pos >> PAGE_SHIFT;
struct page *page;
int status = 0;
BUG_ON(pos + len > iomap->offset + iomap->length);
if (fatal_signal_pending(current))
return -EINTR;
page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
if (!page)
return -ENOMEM;
if (iomap->type == IOMAP_INLINE)
iomap_read_inline_data(inode, page, iomap);
else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
status = __block_write_begin_int(page, pos, len, NULL, iomap);
else
status = __iomap_write_begin(inode, pos, len, page, iomap);
if (unlikely(status)) {
unlock_page(page);
put_page(page);
page = NULL;
iomap_write_failed(inode, pos, len);
}
*pagep = page;
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->mem_cgroup 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 int
__iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
unsigned copied, struct page *page, struct iomap *iomap)
{
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))) {
copied = 0;
} else {
iomap_set_range_uptodate(page, offset_in_page(pos), len);
iomap_set_page_dirty(page);
}
return __generic_write_end(inode, pos, copied, page);
}
static int
iomap_write_end_inline(struct inode *inode, struct page *page,
struct iomap *iomap, loff_t pos, unsigned copied)
{
void *addr;
WARN_ON_ONCE(!PageUptodate(page));
BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
addr = kmap_atomic(page);
memcpy(iomap->inline_data + pos, addr + pos, copied);
kunmap_atomic(addr);
mark_inode_dirty(inode);
__generic_write_end(inode, pos, copied, page);
return copied;
}
static int
iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
unsigned copied, struct page *page, struct iomap *iomap)
{
int ret;
if (iomap->type == IOMAP_INLINE) {
ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
} else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
ret = generic_write_end(NULL, inode->i_mapping, pos, len,
copied, page, NULL);
} else {
ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
}
if (iomap->page_done)
iomap->page_done(inode, pos, copied, page, iomap);
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 iov_iter *i = data;
long status = 0;
ssize_t written = 0;
unsigned int flags = AOP_FLAG_NOFS;
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, flags, &page,
iomap);
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);
flush_dcache_page(page);
status = iomap_write_end(inode, pos, bytes, copied, page,
iomap);
if (unlikely(status < 0))
break;
copied = status;
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 struct page *
__iomap_read_page(struct inode *inode, loff_t offset)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
if (IS_ERR(page))
return page;
if (!PageUptodate(page)) {
put_page(page);
return ERR_PTR(-EIO);
}
return page;
}
static loff_t
iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
{
long status = 0;
ssize_t written = 0;
do {
struct page *page, *rpage;
unsigned long offset; /* Offset into pagecache page */
unsigned long bytes; /* Bytes to write to page */
offset = offset_in_page(pos);
bytes = min_t(loff_t, PAGE_SIZE - offset, length);
rpage = __iomap_read_page(inode, pos);
if (IS_ERR(rpage))
return PTR_ERR(rpage);
status = iomap_write_begin(inode, pos, bytes,
AOP_FLAG_NOFS, &page, iomap);
put_page(rpage);
if (unlikely(status))
return status;
WARN_ON_ONCE(!PageUptodate(page));
status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
if (unlikely(status <= 0)) {
if (WARN_ON_ONCE(status == 0))
return -EIO;
return status;
}
cond_resched();
pos += status;
written += status;
length -= status;
balance_dirty_pages_ratelimited(inode->i_mapping);
} while (length);
return written;
}
int
iomap_file_dirty(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_dirty_actor);
if (ret <= 0)
return ret;
pos += ret;
len -= ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(iomap_file_dirty);
static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
unsigned bytes, struct iomap *iomap)
{
struct page *page;
int status;
status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page,
iomap);
if (status)
return status;
zero_user(page, offset, bytes);
mark_page_accessed(page);
return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
}
static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
struct iomap *iomap)
{
return __dax_zero_page_range(iomap->bdev, iomap->dax_dev,
iomap_sector(iomap, pos & PAGE_MASK), offset, bytes);
}
static loff_t
iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
void *data, struct iomap *iomap)
{
bool *did_zero = data;
loff_t written = 0;
int status;
/* already zeroed? we're done. */
if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
return count;
do {
unsigned offset, bytes;
offset = offset_in_page(pos);
bytes = min_t(loff_t, PAGE_SIZE - offset, count);
if (IS_DAX(inode))
status = iomap_dax_zero(pos, offset, bytes, iomap);
else
status = iomap_zero(inode, pos, offset, bytes, iomap);
if (status < 0)
return status;
pos += bytes;
count -= bytes;
written += bytes;
if (did_zero)
*did_zero = true;
} while (count > 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 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, size;
ssize_t ret;
lock_page(page);
size = i_size_read(inode);
if ((page->mapping != inode->i_mapping) ||
(page_offset(page) > size)) {
/* We overload EFAULT to mean page got truncated */
ret = -EFAULT;
goto out_unlock;
}
/* page is wholly or partially inside EOF */
if (((page->index + 1) << PAGE_SHIFT) > size)
length = offset_in_page(size);
else
length = PAGE_SIZE;
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);
struct fiemap_ctx {
struct fiemap_extent_info *fi;
struct iomap prev;
};
static int iomap_to_fiemap(struct fiemap_extent_info *fi,
struct iomap *iomap, u32 flags)
{
switch (iomap->type) {
case IOMAP_HOLE:
/* skip holes */
return 0;
case IOMAP_DELALLOC:
flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
break;
case IOMAP_MAPPED:
break;
case IOMAP_UNWRITTEN:
flags |= FIEMAP_EXTENT_UNWRITTEN;
break;
case IOMAP_INLINE:
flags |= FIEMAP_EXTENT_DATA_INLINE;
break;
}
if (iomap->flags & IOMAP_F_MERGED)
flags |= FIEMAP_EXTENT_MERGED;
if (iomap->flags & IOMAP_F_SHARED)
flags |= FIEMAP_EXTENT_SHARED;
return fiemap_fill_next_extent(fi, iomap->offset,
iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0,
iomap->length, flags);
}
static loff_t
iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
{
struct fiemap_ctx *ctx = data;
loff_t ret = length;
if (iomap->type == IOMAP_HOLE)
return length;
ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
ctx->prev = *iomap;
switch (ret) {
case 0: /* success */
return length;
case 1: /* extent array full */
return 0;
default:
return ret;
}
}
int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
loff_t start, loff_t len, const struct iomap_ops *ops)
{
struct fiemap_ctx ctx;
loff_t ret;
memset(&ctx, 0, sizeof(ctx));
ctx.fi = fi;
ctx.prev.type = IOMAP_HOLE;
ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
if (ret)
return ret;
if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
ret = filemap_write_and_wait(inode->i_mapping);
if (ret)
return ret;
}
while (len > 0) {
ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
iomap_fiemap_actor);
/* inode with no (attribute) mapping will give ENOENT */
if (ret == -ENOENT)
break;
if (ret < 0)
return ret;
if (ret == 0)
break;
start += ret;
len -= ret;
}
if (ctx.prev.type != IOMAP_HOLE) {
ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
if (ret < 0)
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(iomap_fiemap);
/*
* Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
* Returns true if found and updates @lastoff to the offset in file.
*/
static bool
page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
int whence)
{
const struct address_space_operations *ops = inode->i_mapping->a_ops;
unsigned int bsize = i_blocksize(inode), off;
bool seek_data = whence == SEEK_DATA;
loff_t poff = page_offset(page);
if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
return false;
if (*lastoff < poff) {
/*
* Last offset smaller than the start of the page means we found
* a hole:
*/
if (whence == SEEK_HOLE)
return true;
*lastoff = poff;
}
/*
* Just check the page unless we can and should check block ranges:
*/
if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
return PageUptodate(page) == seek_data;
lock_page(page);
if (unlikely(page->mapping != inode->i_mapping))
goto out_unlock_not_found;
for (off = 0; off < PAGE_SIZE; off += bsize) {
if (offset_in_page(*lastoff) >= off + bsize)
continue;
if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
unlock_page(page);
return true;
}
*lastoff = poff + off + bsize;
}
out_unlock_not_found:
unlock_page(page);
return false;
}
/*
* Seek for SEEK_DATA / SEEK_HOLE in the page cache.
*
* Within unwritten extents, the page cache determines which parts are holes
* and which are data: uptodate buffer heads count as data; everything else
* counts as a hole.
*
* Returns the resulting offset on successs, and -ENOENT otherwise.
*/
static loff_t
page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
int whence)
{
pgoff_t index = offset >> PAGE_SHIFT;
pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
loff_t lastoff = offset;
struct pagevec pvec;
if (length <= 0)
return -ENOENT;
pagevec_init(&pvec);
do {
unsigned nr_pages, i;
nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
end - 1);
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
if (page_seek_hole_data(inode, page, &lastoff, whence))
goto check_range;
lastoff = page_offset(page) + PAGE_SIZE;
}
pagevec_release(&pvec);
} while (index < end);
/* When no page at lastoff and we are not done, we found a hole. */
if (whence != SEEK_HOLE)
goto not_found;
check_range:
if (lastoff < offset + length)
goto out;
not_found:
lastoff = -ENOENT;
out:
pagevec_release(&pvec);
return lastoff;
}
static loff_t
iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
void *data, struct iomap *iomap)
{
switch (iomap->type) {
case IOMAP_UNWRITTEN:
offset = page_cache_seek_hole_data(inode, offset, length,
SEEK_HOLE);
if (offset < 0)
return length;
/* fall through */
case IOMAP_HOLE:
*(loff_t *)data = offset;
return 0;
default:
return length;
}
}
loff_t
iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
{
loff_t size = i_size_read(inode);
loff_t length = size - offset;
loff_t ret;
/* Nothing to be found before or beyond the end of the file. */
if (offset < 0 || offset >= size)
return -ENXIO;
while (length > 0) {
ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
&offset, iomap_seek_hole_actor);
if (ret < 0)
return ret;
if (ret == 0)
break;
offset += ret;
length -= ret;
}
return offset;
}
EXPORT_SYMBOL_GPL(iomap_seek_hole);
static loff_t
iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,
void *data, struct iomap *iomap)
{
switch (iomap->type) {
case IOMAP_HOLE:
return length;
case IOMAP_UNWRITTEN:
offset = page_cache_seek_hole_data(inode, offset, length,
SEEK_DATA);
if (offset < 0)
return length;
/*FALLTHRU*/
default:
*(loff_t *)data = offset;
return 0;
}
}
loff_t
iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
{
loff_t size = i_size_read(inode);
loff_t length = size - offset;
loff_t ret;
/* Nothing to be found before or beyond the end of the file. */
if (offset < 0 || offset >= size)
return -ENXIO;
while (length > 0) {
ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
&offset, iomap_seek_data_actor);
if (ret < 0)
return ret;
if (ret == 0)
break;
offset += ret;
length -= ret;
}
if (length <= 0)
return -ENXIO;
return offset;
}
EXPORT_SYMBOL_GPL(iomap_seek_data);
/*
* Private flags for iomap_dio, must not overlap with the public ones in
* iomap.h:
*/
#define IOMAP_DIO_WRITE_FUA (1 << 28)
#define IOMAP_DIO_NEED_SYNC (1 << 29)
#define IOMAP_DIO_WRITE (1 << 30)
#define IOMAP_DIO_DIRTY (1 << 31)
struct iomap_dio {
struct kiocb *iocb;
iomap_dio_end_io_t *end_io;
loff_t i_size;
loff_t size;
atomic_t ref;
unsigned flags;
int error;
bool wait_for_completion;
union {
/* used during submission and for synchronous completion: */
struct {
struct iov_iter *iter;
struct task_struct *waiter;
struct request_queue *last_queue;
blk_qc_t cookie;
} submit;
/* used for aio completion: */
struct {
struct work_struct work;
} aio;
};
};
static ssize_t iomap_dio_complete(struct iomap_dio *dio)
{
struct kiocb *iocb = dio->iocb;
struct inode *inode = file_inode(iocb->ki_filp);
loff_t offset = iocb->ki_pos;
ssize_t ret;
if (dio->end_io) {
ret = dio->end_io(iocb,
dio->error ? dio->error : dio->size,
dio->flags);
} else {
ret = dio->error;
}
if (likely(!ret)) {
ret = dio->size;
/* check for short read */
if (offset + ret > dio->i_size &&
!(dio->flags & IOMAP_DIO_WRITE))
ret = dio->i_size - offset;
iocb->ki_pos += ret;
}
/*
* Try again to invalidate clean pages which might have been cached by
* non-direct readahead, or faulted in by get_user_pages() if the source
* of the write was an mmap'ed region of the file we're writing. Either
* one is a pretty crazy thing to do, so we don't support it 100%. If
* this invalidation fails, tough, the write still worked...
*
* And this page cache invalidation has to be after dio->end_io(), as
* some filesystems convert unwritten extents to real allocations in
* end_io() when necessary, otherwise a racing buffer read would cache
* zeros from unwritten extents.
*/
if (!dio->error &&
(dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) {
int err;
err = invalidate_inode_pages2_range(inode->i_mapping,
offset >> PAGE_SHIFT,
(offset + dio->size - 1) >> PAGE_SHIFT);
if (err)
dio_warn_stale_pagecache(iocb->ki_filp);
}
/*
* If this is a DSYNC write, make sure we push it to stable storage now
* that we've written data.
*/
if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
ret = generic_write_sync(iocb, ret);
inode_dio_end(file_inode(iocb->ki_filp));
kfree(dio);
return ret;
}
static void iomap_dio_complete_work(struct work_struct *work)
{
struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
struct kiocb *iocb = dio->iocb;
iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
}
/*
* Set an error in the dio if none is set yet. We have to use cmpxchg
* as the submission context and the completion context(s) can race to
* update the error.
*/
static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
{
cmpxchg(&dio->error, 0, ret);
}
static void iomap_dio_bio_end_io(struct bio *bio)
{
struct iomap_dio *dio = bio->bi_private;
bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
if (bio->bi_status)
iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
if (atomic_dec_and_test(&dio->ref)) {
if (dio->wait_for_completion) {
struct task_struct *waiter = dio->submit.waiter;
WRITE_ONCE(dio->submit.waiter, NULL);
wake_up_process(waiter);
} else if (dio->flags & IOMAP_DIO_WRITE) {
struct inode *inode = file_inode(dio->iocb->ki_filp);
INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
} else {
iomap_dio_complete_work(&dio->aio.work);
}
}
if (should_dirty) {
bio_check_pages_dirty(bio);
} else {
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i)
put_page(bvec->bv_page);
bio_put(bio);
}
}
static blk_qc_t
iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
unsigned len)
{
struct page *page = ZERO_PAGE(0);
struct bio *bio;
bio = bio_alloc(GFP_KERNEL, 1);
bio_set_dev(bio, iomap->bdev);
bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
bio->bi_private = dio;
bio->bi_end_io = iomap_dio_bio_end_io;
get_page(page);
__bio_add_page(bio, page, len, 0);
bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
atomic_inc(&dio->ref);
return submit_bio(bio);
}
static loff_t
iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
struct iomap_dio *dio, struct iomap *iomap)
{
unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
unsigned int fs_block_size = i_blocksize(inode), pad;
unsigned int align = iov_iter_alignment(dio->submit.iter);
struct iov_iter iter;
struct bio *bio;
bool need_zeroout = false;
bool use_fua = false;
int nr_pages, ret = 0;
size_t copied = 0;
if ((pos | length | align) & ((1 << blkbits) - 1))
return -EINVAL;
if (iomap->type == IOMAP_UNWRITTEN) {
dio->flags |= IOMAP_DIO_UNWRITTEN;
need_zeroout = true;
}
if (iomap->flags & IOMAP_F_SHARED)
dio->flags |= IOMAP_DIO_COW;
if (iomap->flags & IOMAP_F_NEW) {
need_zeroout = true;
} else if (iomap->type == IOMAP_MAPPED) {
/*
* Use a FUA write if we need datasync semantics, this is a pure
* data IO that doesn't require any metadata updates (including
* after IO completion such as unwritten extent conversion) and
* the underlying device supports FUA. This allows us to avoid
* cache flushes on IO completion.
*/
if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
(dio->flags & IOMAP_DIO_WRITE_FUA) &&
blk_queue_fua(bdev_get_queue(iomap->bdev)))
use_fua = true;
}
/*
* Operate on a partial iter trimmed to the extent we were called for.
* We'll update the iter in the dio once we're done with this extent.
*/
iter = *dio->submit.iter;
iov_iter_truncate(&iter, length);
nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
if (nr_pages <= 0)
return nr_pages;
if (need_zeroout) {
/* zero out from the start of the block to the write offset */
pad = pos & (fs_block_size - 1);
if (pad)
iomap_dio_zero(dio, iomap, pos - pad, pad);
}
do {
size_t n;
if (dio->error) {
iov_iter_revert(dio->submit.iter, copied);
return 0;
}
bio = bio_alloc(GFP_KERNEL, nr_pages);
bio_set_dev(bio, iomap->bdev);
bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
bio->bi_write_hint = dio->iocb->ki_hint;
bio->bi_ioprio = dio->iocb->ki_ioprio;
bio->bi_private = dio;
bio->bi_end_io = iomap_dio_bio_end_io;
ret = bio_iov_iter_get_pages(bio, &iter);
if (unlikely(ret)) {
/*
* We have to stop part way through an IO. We must fall
* through to the sub-block tail zeroing here, otherwise
* this short IO may expose stale data in the tail of
* the block we haven't written data to.
*/
bio_put(bio);
goto zero_tail;
}
n = bio->bi_iter.bi_size;
if (dio->flags & IOMAP_DIO_WRITE) {
bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
if (use_fua)
bio->bi_opf |= REQ_FUA;
else
dio->flags &= ~IOMAP_DIO_WRITE_FUA;
task_io_account_write(n);
} else {
bio->bi_opf = REQ_OP_READ;
if (dio->flags & IOMAP_DIO_DIRTY)
bio_set_pages_dirty(bio);
}
iov_iter_advance(dio->submit.iter, n);
dio->size += n;
pos += n;
copied += n;
nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
atomic_inc(&dio->ref);
dio->submit.last_queue = bdev_get_queue(iomap->bdev);
dio->submit.cookie = submit_bio(bio);
} while (nr_pages);
/*
* We need to zeroout the tail of a sub-block write if the extent type
* requires zeroing or the write extends beyond EOF. If we don't zero
* the block tail in the latter case, we can expose stale data via mmap
* reads of the EOF block.
*/
zero_tail:
if (need_zeroout ||
((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
/* zero out from the end of the write to the end of the block */
pad = pos & (fs_block_size - 1);
if (pad)
iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
}
return copied ? copied : ret;
}
static loff_t
iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
{
length = iov_iter_zero(length, dio->submit.iter);
dio->size += length;
return length;
}
static loff_t
iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
struct iomap_dio *dio, struct iomap *iomap)
{
struct iov_iter *iter = dio->submit.iter;
size_t copied;
BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
if (dio->flags & IOMAP_DIO_WRITE) {
loff_t size = inode->i_size;
if (pos > size)
memset(iomap->inline_data + size, 0, pos - size);
copied = copy_from_iter(iomap->inline_data + pos, length, iter);
if (copied) {
if (pos + copied > size)
i_size_write(inode, pos + copied);
mark_inode_dirty(inode);
}
} else {
copied = copy_to_iter(iomap->inline_data + pos, length, iter);
}
dio->size += copied;
return copied;
}
static loff_t
iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap)
{
struct iomap_dio *dio = data;
switch (iomap->type) {
case IOMAP_HOLE:
if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
return -EIO;
return iomap_dio_hole_actor(length, dio);
case IOMAP_UNWRITTEN:
if (!(dio->flags & IOMAP_DIO_WRITE))
return iomap_dio_hole_actor(length, dio);
return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
case IOMAP_MAPPED:
return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
case IOMAP_INLINE:
return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
default:
WARN_ON_ONCE(1);
return -EIO;
}
}
/*
* iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
* is being issued as AIO or not. This allows us to optimise pure data writes
* to use REQ_FUA rather than requiring generic_write_sync() to issue a
* REQ_FLUSH post write. This is slightly tricky because a single request here
* can be mapped into multiple disjoint IOs and only a subset of the IOs issued
* may be pure data writes. In that case, we still need to do a full data sync
* completion.
*/
ssize_t
iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
{
struct address_space *mapping = iocb->ki_filp->f_mapping;
struct inode *inode = file_inode(iocb->ki_filp);
size_t count = iov_iter_count(iter);
loff_t pos = iocb->ki_pos, start = pos;
loff_t end = iocb->ki_pos + count - 1, ret = 0;
unsigned int flags = IOMAP_DIRECT;
struct blk_plug plug;
struct iomap_dio *dio;
lockdep_assert_held(&inode->i_rwsem);
if (!count)
return 0;
dio = kmalloc(sizeof(*dio), GFP_KERNEL);
if (!dio)
return -ENOMEM;
dio->iocb = iocb;
atomic_set(&dio->ref, 1);
dio->size = 0;
dio->i_size = i_size_read(inode);
dio->end_io = end_io;
dio->error = 0;
dio->flags = 0;
dio->wait_for_completion = is_sync_kiocb(iocb);
dio->submit.iter = iter;
dio->submit.waiter = current;
dio->submit.cookie = BLK_QC_T_NONE;
dio->submit.last_queue = NULL;
if (iov_iter_rw(iter) == READ) {
if (pos >= dio->i_size)
goto out_free_dio;
if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ)
dio->flags |= IOMAP_DIO_DIRTY;
} else {
flags |= IOMAP_WRITE;
dio->flags |= IOMAP_DIO_WRITE;
/* for data sync or sync, we need sync completion processing */
if (iocb->ki_flags & IOCB_DSYNC)
dio->flags |= IOMAP_DIO_NEED_SYNC;
/*
* For datasync only writes, we optimistically try using FUA for
* this IO. Any non-FUA write that occurs will clear this flag,
* hence we know before completion whether a cache flush is
* necessary.
*/
if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
dio->flags |= IOMAP_DIO_WRITE_FUA;
}
if (iocb->ki_flags & IOCB_NOWAIT) {
if (filemap_range_has_page(mapping, start, end)) {
ret = -EAGAIN;
goto out_free_dio;
}
flags |= IOMAP_NOWAIT;
}
ret = filemap_write_and_wait_range(mapping, start, end);
if (ret)
goto out_free_dio;
/*
* Try to invalidate cache pages for the range we're direct
* writing. If this invalidation fails, tough, the write will
* still work, but racing two incompatible write paths is a
* pretty crazy thing to do, so we don't support it 100%.
*/
ret = invalidate_inode_pages2_range(mapping,
start >> PAGE_SHIFT, end >> PAGE_SHIFT);
if (ret)
dio_warn_stale_pagecache(iocb->ki_filp);
ret = 0;
if (iov_iter_rw(iter) == WRITE && !dio->wait_for_completion &&
!inode->i_sb->s_dio_done_wq) {
ret = sb_init_dio_done_wq(inode->i_sb);
if (ret < 0)
goto out_free_dio;
}
inode_dio_begin(inode);
blk_start_plug(&plug);
do {
ret = iomap_apply(inode, pos, count, flags, ops, dio,
iomap_dio_actor);
if (ret <= 0) {
/* magic error code to fall back to buffered I/O */
if (ret == -ENOTBLK) {
dio->wait_for_completion = true;
ret = 0;
}
break;
}
pos += ret;
if (iov_iter_rw(iter) == READ && pos >= dio->i_size)
break;
} while ((count = iov_iter_count(iter)) > 0);
blk_finish_plug(&plug);
if (ret < 0)
iomap_dio_set_error(dio, ret);
/*
* If all the writes we issued were FUA, we don't need to flush the
* cache on IO completion. Clear the sync flag for this case.
*/
if (dio->flags & IOMAP_DIO_WRITE_FUA)
dio->flags &= ~IOMAP_DIO_NEED_SYNC;
if (!atomic_dec_and_test(&dio->ref)) {
if (!dio->wait_for_completion)
return -EIOCBQUEUED;
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!READ_ONCE(dio->submit.waiter))
break;
if (!(iocb->ki_flags & IOCB_HIPRI) ||
!dio->submit.last_queue ||
!blk_poll(dio->submit.last_queue,
dio->submit.cookie))
io_schedule();
}
__set_current_state(TASK_RUNNING);
}
ret = iomap_dio_complete(dio);
return ret;
out_free_dio:
kfree(dio);
return ret;
}
EXPORT_SYMBOL_GPL(iomap_dio_rw);
/* Swapfile activation */
#ifdef CONFIG_SWAP
struct iomap_swapfile_info {
struct iomap iomap; /* accumulated iomap */
struct swap_info_struct *sis;
uint64_t lowest_ppage; /* lowest physical addr seen (pages) */
uint64_t highest_ppage; /* highest physical addr seen (pages) */
unsigned long nr_pages; /* number of pages collected */
int nr_extents; /* extent count */
};
/*
* Collect physical extents for this swap file. Physical extents reported to
* the swap code must be trimmed to align to a page boundary. The logical
* offset within the file is irrelevant since the swapfile code maps logical
* page numbers of the swap device to the physical page-aligned extents.
*/
static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
{
struct iomap *iomap = &isi->iomap;
unsigned long nr_pages;
uint64_t first_ppage;
uint64_t first_ppage_reported;
uint64_t next_ppage;
int error;
/*
* Round the start up and the end down so that the physical
* extent aligns to a page boundary.
*/
first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
PAGE_SHIFT;
/* Skip too-short physical extents. */
if (first_ppage >= next_ppage)
return 0;
nr_pages = next_ppage - first_ppage;
/*
* Calculate how much swap space we're adding; the first page contains
* the swap header and doesn't count. The mm still wants that first
* page fed to add_swap_extent, however.
*/
first_ppage_reported = first_ppage;
if (iomap->offset == 0)
first_ppage_reported++;
if (isi->lowest_ppage > first_ppage_reported)
isi->lowest_ppage = first_ppage_reported;
if (isi->highest_ppage < (next_ppage - 1))
isi->highest_ppage = next_ppage - 1;
/* Add extent, set up for the next call. */
error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
if (error < 0)
return error;
isi->nr_extents += error;
isi->nr_pages += nr_pages;
return 0;
}
/*
* Accumulate iomaps for this swap file. We have to accumulate iomaps because
* swap only cares about contiguous page-aligned physical extents and makes no
* distinction between written and unwritten extents.
*/
static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
loff_t count, void *data, struct iomap *iomap)
{
struct iomap_swapfile_info *isi = data;
int error;
switch (iomap->type) {
case IOMAP_MAPPED:
case IOMAP_UNWRITTEN:
/* Only real or unwritten extents. */
break;
case IOMAP_INLINE:
/* No inline data. */
pr_err("swapon: file is inline\n");
return -EINVAL;
default:
pr_err("swapon: file has unallocated extents\n");
return -EINVAL;
}
/* No uncommitted metadata or shared blocks. */
if (iomap->flags & IOMAP_F_DIRTY) {
pr_err("swapon: file is not committed\n");
return -EINVAL;
}
if (iomap->flags & IOMAP_F_SHARED) {
pr_err("swapon: file has shared extents\n");
return -EINVAL;
}
/* Only one bdev per swap file. */
if (iomap->bdev != isi->sis->bdev) {
pr_err("swapon: file is on multiple devices\n");
return -EINVAL;
}
if (isi->iomap.length == 0) {
/* No accumulated extent, so just store it. */
memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
} else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
/* Append this to the accumulated extent. */
isi->iomap.length += iomap->length;
} else {
/* Otherwise, add the retained iomap and store this one. */
error = iomap_swapfile_add_extent(isi);
if (error)
return error;
memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
}
return count;
}
/*
* Iterate a swap file's iomaps to construct physical extents that can be
* passed to the swapfile subsystem.
*/
int iomap_swapfile_activate(struct swap_info_struct *sis,
struct file *swap_file, sector_t *pagespan,
const struct iomap_ops *ops)
{
struct iomap_swapfile_info isi = {
.sis = sis,
.lowest_ppage = (sector_t)-1ULL,
};
struct address_space *mapping = swap_file->f_mapping;
struct inode *inode = mapping->host;
loff_t pos = 0;
loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
loff_t ret;
/*
* Persist all file mapping metadata so that we won't have any
* IOMAP_F_DIRTY iomaps.
*/
ret = vfs_fsync(swap_file, 1);
if (ret)
return ret;
while (len > 0) {
ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
ops, &isi, iomap_swapfile_activate_actor);
if (ret <= 0)
return ret;
pos += ret;
len -= ret;
}
if (isi.iomap.length) {
ret = iomap_swapfile_add_extent(&isi);
if (ret)
return ret;
}
*pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
sis->max = isi.nr_pages;
sis->pages = isi.nr_pages - 1;
sis->highest_bit = isi.nr_pages - 1;
return isi.nr_extents;
}
EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
#endif /* CONFIG_SWAP */
static loff_t
iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
void *data, struct iomap *iomap)
{
sector_t *bno = data, addr;
if (iomap->type == IOMAP_MAPPED) {
addr = (pos - iomap->offset + iomap->addr) >> inode->i_blkbits;
if (addr > INT_MAX)
WARN(1, "would truncate bmap result\n");
else
*bno = addr;
}
return 0;
}
/* legacy ->bmap interface. 0 is the error return (!) */
sector_t
iomap_bmap(struct address_space *mapping, sector_t bno,
const struct iomap_ops *ops)
{
struct inode *inode = mapping->host;
loff_t pos = bno << inode->i_blkbits;
unsigned blocksize = i_blocksize(inode);
if (filemap_write_and_wait(mapping))
return 0;
bno = 0;
iomap_apply(inode, pos, blocksize, 0, ops, &bno, iomap_bmap_actor);
return bno;
}
EXPORT_SYMBOL_GPL(iomap_bmap);