linux/fs/xfs/xfs_aops.c
Dave Chinner 150d5be09c xfs: remove xfs_cancel_ioend
We currently have code to cancel ioends being built because we
change bufferhead state as we build the ioend. On error, this needs
to be unwound and so we have cancelling code that walks the buffers
on the ioend chain and undoes these state changes.

However, the IO submission path already handles state changes for
buffers when a submission error occurs, so we don't really need a
separate cancel function to do this - we can simply submit the
ioend chain with the specific error and it will be cancelled rather
than submitted.

Hence we can remove the explicit cancel code and just rely on
submission to deal with the error correctly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-02-15 17:21:12 +11:00

2004 lines
54 KiB
C

/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_alloc.h"
#include "xfs_error.h"
#include "xfs_iomap.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_bmap_btree.h"
#include <linux/gfp.h>
#include <linux/mpage.h>
#include <linux/pagevec.h>
#include <linux/writeback.h>
void
xfs_count_page_state(
struct page *page,
int *delalloc,
int *unwritten)
{
struct buffer_head *bh, *head;
*delalloc = *unwritten = 0;
bh = head = page_buffers(page);
do {
if (buffer_unwritten(bh))
(*unwritten) = 1;
else if (buffer_delay(bh))
(*delalloc) = 1;
} while ((bh = bh->b_this_page) != head);
}
STATIC struct block_device *
xfs_find_bdev_for_inode(
struct inode *inode)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
if (XFS_IS_REALTIME_INODE(ip))
return mp->m_rtdev_targp->bt_bdev;
else
return mp->m_ddev_targp->bt_bdev;
}
/*
* We're now finished for good with this ioend structure.
* Update the page state via the associated buffer_heads,
* release holds on the inode and bio, and finally free
* up memory. Do not use the ioend after this.
*/
STATIC void
xfs_destroy_ioend(
xfs_ioend_t *ioend)
{
struct buffer_head *bh, *next;
for (bh = ioend->io_buffer_head; bh; bh = next) {
next = bh->b_private;
bh->b_end_io(bh, !ioend->io_error);
}
mempool_free(ioend, xfs_ioend_pool);
}
/*
* Fast and loose check if this write could update the on-disk inode size.
*/
static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
{
return ioend->io_offset + ioend->io_size >
XFS_I(ioend->io_inode)->i_d.di_size;
}
STATIC int
xfs_setfilesize_trans_alloc(
struct xfs_ioend *ioend)
{
struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
struct xfs_trans *tp;
int error;
tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_fsyncts, 0, 0);
if (error) {
xfs_trans_cancel(tp);
return error;
}
ioend->io_append_trans = tp;
/*
* We may pass freeze protection with a transaction. So tell lockdep
* we released it.
*/
__sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
/*
* We hand off the transaction to the completion thread now, so
* clear the flag here.
*/
current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
return 0;
}
/*
* Update on-disk file size now that data has been written to disk.
*/
STATIC int
xfs_setfilesize(
struct xfs_inode *ip,
struct xfs_trans *tp,
xfs_off_t offset,
size_t size)
{
xfs_fsize_t isize;
xfs_ilock(ip, XFS_ILOCK_EXCL);
isize = xfs_new_eof(ip, offset + size);
if (!isize) {
xfs_iunlock(ip, XFS_ILOCK_EXCL);
xfs_trans_cancel(tp);
return 0;
}
trace_xfs_setfilesize(ip, offset, size);
ip->i_d.di_size = isize;
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
return xfs_trans_commit(tp);
}
STATIC int
xfs_setfilesize_ioend(
struct xfs_ioend *ioend)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
struct xfs_trans *tp = ioend->io_append_trans;
/*
* The transaction may have been allocated in the I/O submission thread,
* thus we need to mark ourselves as being in a transaction manually.
* Similarly for freeze protection.
*/
current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
__sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
/* we abort the update if there was an IO error */
if (ioend->io_error) {
xfs_trans_cancel(tp);
return ioend->io_error;
}
return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
}
/*
* Schedule IO completion handling on the final put of an ioend.
*
* If there is no work to do we might as well call it a day and free the
* ioend right now.
*/
STATIC void
xfs_finish_ioend(
struct xfs_ioend *ioend)
{
if (atomic_dec_and_test(&ioend->io_remaining)) {
struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
if (ioend->io_type == XFS_IO_UNWRITTEN)
queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
else if (ioend->io_append_trans)
queue_work(mp->m_data_workqueue, &ioend->io_work);
else
xfs_destroy_ioend(ioend);
}
}
/*
* IO write completion.
*/
STATIC void
xfs_end_io(
struct work_struct *work)
{
xfs_ioend_t *ioend = container_of(work, xfs_ioend_t, io_work);
struct xfs_inode *ip = XFS_I(ioend->io_inode);
int error = 0;
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
ioend->io_error = -EIO;
goto done;
}
/*
* For unwritten extents we need to issue transactions to convert a
* range to normal written extens after the data I/O has finished.
* Detecting and handling completion IO errors is done individually
* for each case as different cleanup operations need to be performed
* on error.
*/
if (ioend->io_type == XFS_IO_UNWRITTEN) {
if (ioend->io_error)
goto done;
error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
ioend->io_size);
} else if (ioend->io_append_trans) {
error = xfs_setfilesize_ioend(ioend);
} else {
ASSERT(!xfs_ioend_is_append(ioend));
}
done:
if (error)
ioend->io_error = error;
xfs_destroy_ioend(ioend);
}
/*
* Allocate and initialise an IO completion structure.
* We need to track unwritten extent write completion here initially.
* We'll need to extend this for updating the ondisk inode size later
* (vs. incore size).
*/
STATIC xfs_ioend_t *
xfs_alloc_ioend(
struct inode *inode,
unsigned int type)
{
xfs_ioend_t *ioend;
ioend = mempool_alloc(xfs_ioend_pool, GFP_NOFS);
/*
* Set the count to 1 initially, which will prevent an I/O
* completion callback from happening before we have started
* all the I/O from calling the completion routine too early.
*/
atomic_set(&ioend->io_remaining, 1);
ioend->io_error = 0;
ioend->io_list = NULL;
ioend->io_type = type;
ioend->io_inode = inode;
ioend->io_buffer_head = NULL;
ioend->io_buffer_tail = NULL;
ioend->io_offset = 0;
ioend->io_size = 0;
ioend->io_append_trans = NULL;
INIT_WORK(&ioend->io_work, xfs_end_io);
return ioend;
}
STATIC int
xfs_map_blocks(
struct inode *inode,
loff_t offset,
struct xfs_bmbt_irec *imap,
int type)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
ssize_t count = 1 << inode->i_blkbits;
xfs_fileoff_t offset_fsb, end_fsb;
int error = 0;
int bmapi_flags = XFS_BMAPI_ENTIRE;
int nimaps = 1;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
if (type == XFS_IO_UNWRITTEN)
bmapi_flags |= XFS_BMAPI_IGSTATE;
xfs_ilock(ip, XFS_ILOCK_SHARED);
ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
(ip->i_df.if_flags & XFS_IFEXTENTS));
ASSERT(offset <= mp->m_super->s_maxbytes);
if (offset + count > mp->m_super->s_maxbytes)
count = mp->m_super->s_maxbytes - offset;
end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
imap, &nimaps, bmapi_flags);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error)
return error;
if (type == XFS_IO_DELALLOC &&
(!nimaps || isnullstartblock(imap->br_startblock))) {
error = xfs_iomap_write_allocate(ip, offset, imap);
if (!error)
trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
return error;
}
#ifdef DEBUG
if (type == XFS_IO_UNWRITTEN) {
ASSERT(nimaps);
ASSERT(imap->br_startblock != HOLESTARTBLOCK);
ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
}
#endif
if (nimaps)
trace_xfs_map_blocks_found(ip, offset, count, type, imap);
return 0;
}
STATIC int
xfs_imap_valid(
struct inode *inode,
struct xfs_bmbt_irec *imap,
xfs_off_t offset)
{
offset >>= inode->i_blkbits;
return offset >= imap->br_startoff &&
offset < imap->br_startoff + imap->br_blockcount;
}
/*
* BIO completion handler for buffered IO.
*/
STATIC void
xfs_end_bio(
struct bio *bio)
{
xfs_ioend_t *ioend = bio->bi_private;
if (!ioend->io_error)
ioend->io_error = bio->bi_error;
/* Toss bio and pass work off to an xfsdatad thread */
bio->bi_private = NULL;
bio->bi_end_io = NULL;
bio_put(bio);
xfs_finish_ioend(ioend);
}
STATIC void
xfs_submit_ioend_bio(
struct writeback_control *wbc,
xfs_ioend_t *ioend,
struct bio *bio)
{
atomic_inc(&ioend->io_remaining);
bio->bi_private = ioend;
bio->bi_end_io = xfs_end_bio;
submit_bio(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE, bio);
}
STATIC struct bio *
xfs_alloc_ioend_bio(
struct buffer_head *bh)
{
struct bio *bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
ASSERT(bio->bi_private == NULL);
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bio->bi_bdev = bh->b_bdev;
return bio;
}
STATIC void
xfs_start_buffer_writeback(
struct buffer_head *bh)
{
ASSERT(buffer_mapped(bh));
ASSERT(buffer_locked(bh));
ASSERT(!buffer_delay(bh));
ASSERT(!buffer_unwritten(bh));
mark_buffer_async_write(bh);
set_buffer_uptodate(bh);
clear_buffer_dirty(bh);
}
STATIC void
xfs_start_page_writeback(
struct page *page,
int clear_dirty,
int buffers)
{
ASSERT(PageLocked(page));
ASSERT(!PageWriteback(page));
/*
* if the page was not fully cleaned, we need to ensure that the higher
* layers come back to it correctly. That means we need to keep the page
* dirty, and for WB_SYNC_ALL writeback we need to ensure the
* PAGECACHE_TAG_TOWRITE index mark is not removed so another attempt to
* write this page in this writeback sweep will be made.
*/
if (clear_dirty) {
clear_page_dirty_for_io(page);
set_page_writeback(page);
} else
set_page_writeback_keepwrite(page);
unlock_page(page);
/* If no buffers on the page are to be written, finish it here */
if (!buffers)
end_page_writeback(page);
}
static inline int xfs_bio_add_buffer(struct bio *bio, struct buffer_head *bh)
{
return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
}
/*
* Submit all of the bios for all of the ioends we have saved up, covering the
* initial writepage page and also any probed pages.
*
* Because we may have multiple ioends spanning a page, we need to start
* writeback on all the buffers before we submit them for I/O. If we mark the
* buffers as we got, then we can end up with a page that only has buffers
* marked async write and I/O complete on can occur before we mark the other
* buffers async write.
*
* The end result of this is that we trip a bug in end_page_writeback() because
* we call it twice for the one page as the code in end_buffer_async_write()
* assumes that all buffers on the page are started at the same time.
*
* The fix is two passes across the ioend list - one to start writeback on the
* buffer_heads, and then submit them for I/O on the second pass.
*
* If @fail 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 ioend chain rather
* than submit it to IO. This typically only happens on a filesystem shutdown.
*/
STATIC void
xfs_submit_ioend(
struct writeback_control *wbc,
xfs_ioend_t *ioend,
int fail)
{
xfs_ioend_t *head = ioend;
xfs_ioend_t *next;
struct buffer_head *bh;
struct bio *bio;
sector_t lastblock = 0;
/* Pass 1 - start writeback */
do {
next = ioend->io_list;
for (bh = ioend->io_buffer_head; bh; bh = bh->b_private)
xfs_start_buffer_writeback(bh);
} while ((ioend = next) != NULL);
/* Pass 2 - submit I/O */
ioend = head;
do {
next = ioend->io_list;
bio = NULL;
/*
* 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.
*/
if (fail) {
ioend->io_error = fail;
xfs_finish_ioend(ioend);
continue;
}
for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {
if (!bio) {
retry:
bio = xfs_alloc_ioend_bio(bh);
} else if (bh->b_blocknr != lastblock + 1) {
xfs_submit_ioend_bio(wbc, ioend, bio);
goto retry;
}
if (xfs_bio_add_buffer(bio, bh) != bh->b_size) {
xfs_submit_ioend_bio(wbc, ioend, bio);
goto retry;
}
lastblock = bh->b_blocknr;
}
if (bio)
xfs_submit_ioend_bio(wbc, ioend, bio);
xfs_finish_ioend(ioend);
} while ((ioend = next) != NULL);
}
/*
* Test to see if we've been building up a completion structure for
* earlier buffers -- if so, we try to append to this ioend if we
* can, otherwise we finish off any current ioend and start another.
* Return true if we've finished the given ioend.
*/
STATIC void
xfs_add_to_ioend(
struct inode *inode,
struct buffer_head *bh,
xfs_off_t offset,
unsigned int type,
xfs_ioend_t **result,
int need_ioend)
{
xfs_ioend_t *ioend = *result;
if (!ioend || need_ioend || type != ioend->io_type) {
xfs_ioend_t *previous = *result;
ioend = xfs_alloc_ioend(inode, type);
ioend->io_offset = offset;
ioend->io_buffer_head = bh;
ioend->io_buffer_tail = bh;
if (previous)
previous->io_list = ioend;
*result = ioend;
} else {
ioend->io_buffer_tail->b_private = bh;
ioend->io_buffer_tail = bh;
}
bh->b_private = NULL;
ioend->io_size += bh->b_size;
}
STATIC void
xfs_map_buffer(
struct inode *inode,
struct buffer_head *bh,
struct xfs_bmbt_irec *imap,
xfs_off_t offset)
{
sector_t bn;
struct xfs_mount *m = XFS_I(inode)->i_mount;
xfs_off_t iomap_offset = XFS_FSB_TO_B(m, imap->br_startoff);
xfs_daddr_t iomap_bn = xfs_fsb_to_db(XFS_I(inode), imap->br_startblock);
ASSERT(imap->br_startblock != HOLESTARTBLOCK);
ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
bn = (iomap_bn >> (inode->i_blkbits - BBSHIFT)) +
((offset - iomap_offset) >> inode->i_blkbits);
ASSERT(bn || XFS_IS_REALTIME_INODE(XFS_I(inode)));
bh->b_blocknr = bn;
set_buffer_mapped(bh);
}
STATIC void
xfs_map_at_offset(
struct inode *inode,
struct buffer_head *bh,
struct xfs_bmbt_irec *imap,
xfs_off_t offset)
{
ASSERT(imap->br_startblock != HOLESTARTBLOCK);
ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
xfs_map_buffer(inode, bh, imap, offset);
set_buffer_mapped(bh);
clear_buffer_delay(bh);
clear_buffer_unwritten(bh);
}
/*
* Test if a given page contains at least one buffer of a given @type.
* If @check_all_buffers is true, then we walk all the buffers in the page to
* try to find one of the type passed in. If it is not set, then the caller only
* needs to check the first buffer on the page for a match.
*/
STATIC bool
xfs_check_page_type(
struct page *page,
unsigned int type,
bool check_all_buffers)
{
struct buffer_head *bh;
struct buffer_head *head;
if (PageWriteback(page))
return false;
if (!page->mapping)
return false;
if (!page_has_buffers(page))
return false;
bh = head = page_buffers(page);
do {
if (buffer_unwritten(bh)) {
if (type == XFS_IO_UNWRITTEN)
return true;
} else if (buffer_delay(bh)) {
if (type == XFS_IO_DELALLOC)
return true;
} else if (buffer_dirty(bh) && buffer_mapped(bh)) {
if (type == XFS_IO_OVERWRITE)
return true;
}
/* If we are only checking the first buffer, we are done now. */
if (!check_all_buffers)
break;
} while ((bh = bh->b_this_page) != head);
return false;
}
/*
* Allocate & map buffers for page given the extent map. Write it out.
* except for the original page of a writepage, this is called on
* delalloc/unwritten pages only, for the original page it is possible
* that the page has no mapping at all.
*/
STATIC int
xfs_convert_page(
struct inode *inode,
struct page *page,
loff_t tindex,
struct xfs_bmbt_irec *imap,
xfs_ioend_t **ioendp,
struct writeback_control *wbc)
{
struct buffer_head *bh, *head;
xfs_off_t end_offset;
unsigned long p_offset;
unsigned int type;
int len, page_dirty;
int count = 0, done = 0, uptodate = 1;
xfs_off_t offset = page_offset(page);
if (page->index != tindex)
goto fail;
if (!trylock_page(page))
goto fail;
if (PageWriteback(page))
goto fail_unlock_page;
if (page->mapping != inode->i_mapping)
goto fail_unlock_page;
if (!xfs_check_page_type(page, (*ioendp)->io_type, false))
goto fail_unlock_page;
/*
* page_dirty is initially a count of buffers on the page before
* EOF and is decremented as we move each into a cleanable state.
*
* Derivation:
*
* End offset is the highest offset that this page should represent.
* If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
* will evaluate non-zero and be less than PAGE_CACHE_SIZE and
* hence give us the correct page_dirty count. On any other page,
* it will be zero and in that case we need page_dirty to be the
* count of buffers on the page.
*/
end_offset = min_t(unsigned long long,
(xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
i_size_read(inode));
/*
* If the current map does not span the entire page we are about to try
* to write, then give up. The only way we can write a page that spans
* multiple mappings in a single writeback iteration is via the
* xfs_vm_writepage() function. Data integrity writeback requires the
* entire page to be written in a single attempt, otherwise the part of
* the page we don't write here doesn't get written as part of the data
* integrity sync.
*
* For normal writeback, we also don't attempt to write partial pages
* here as it simply means that write_cache_pages() will see it under
* writeback and ignore the page until some point in the future, at
* which time this will be the only page in the file that needs
* writeback. Hence for more optimal IO patterns, we should always
* avoid partial page writeback due to multiple mappings on a page here.
*/
if (!xfs_imap_valid(inode, imap, end_offset))
goto fail_unlock_page;
len = 1 << inode->i_blkbits;
p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
PAGE_CACHE_SIZE);
p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
page_dirty = p_offset / len;
/*
* The moment we find a buffer that doesn't match our current type
* specification or can't be written, abort the loop and start
* writeback. As per the above xfs_imap_valid() check, only
* xfs_vm_writepage() can handle partial page writeback fully - we are
* limited here to the buffers that are contiguous with the current
* ioend, and hence a buffer we can't write breaks that contiguity and
* we have to defer the rest of the IO to xfs_vm_writepage().
*/
bh = head = page_buffers(page);
do {
if (offset >= end_offset)
break;
if (!buffer_uptodate(bh))
uptodate = 0;
if (!(PageUptodate(page) || buffer_uptodate(bh))) {
done = 1;
break;
}
if (buffer_unwritten(bh) || buffer_delay(bh) ||
buffer_mapped(bh)) {
if (buffer_unwritten(bh))
type = XFS_IO_UNWRITTEN;
else if (buffer_delay(bh))
type = XFS_IO_DELALLOC;
else
type = XFS_IO_OVERWRITE;
/*
* imap should always be valid because of the above
* partial page end_offset check on the imap.
*/
ASSERT(xfs_imap_valid(inode, imap, offset));
lock_buffer(bh);
if (type != XFS_IO_OVERWRITE)
xfs_map_at_offset(inode, bh, imap, offset);
xfs_add_to_ioend(inode, bh, offset, type,
ioendp, done);
page_dirty--;
count++;
} else {
done = 1;
break;
}
} while (offset += len, (bh = bh->b_this_page) != head);
if (uptodate && bh == head)
SetPageUptodate(page);
if (count) {
if (--wbc->nr_to_write <= 0 &&
wbc->sync_mode == WB_SYNC_NONE)
done = 1;
}
xfs_start_page_writeback(page, !page_dirty, count);
return done;
fail_unlock_page:
unlock_page(page);
fail:
return 1;
}
/*
* Convert & write out a cluster of pages in the same extent as defined
* by mp and following the start page.
*/
STATIC void
xfs_cluster_write(
struct inode *inode,
pgoff_t tindex,
struct xfs_bmbt_irec *imap,
xfs_ioend_t **ioendp,
struct writeback_control *wbc,
pgoff_t tlast)
{
struct pagevec pvec;
int done = 0, i;
pagevec_init(&pvec, 0);
while (!done && tindex <= tlast) {
unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);
if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
break;
for (i = 0; i < pagevec_count(&pvec); i++) {
done = xfs_convert_page(inode, pvec.pages[i], tindex++,
imap, ioendp, wbc);
if (done)
break;
}
pagevec_release(&pvec);
cond_resched();
}
}
STATIC void
xfs_vm_invalidatepage(
struct page *page,
unsigned int offset,
unsigned int length)
{
trace_xfs_invalidatepage(page->mapping->host, page, offset,
length);
block_invalidatepage(page, offset, length);
}
/*
* If the page has delalloc buffers on it, we need to punch them out before we
* invalidate the page. If we don't, we leave a stale delalloc mapping on the
* inode that can trip a BUG() in xfs_get_blocks() later on if a direct IO read
* is done on that same region - the delalloc extent is returned when none is
* supposed to be there.
*
* We prevent this by truncating away the delalloc regions on the page before
* invalidating it. Because they are delalloc, we can do this without needing a
* transaction. Indeed - if we get ENOSPC errors, we have to be able to do this
* truncation without a transaction as there is no space left for block
* reservation (typically why we see a ENOSPC in writeback).
*
* This is not a performance critical path, so for now just do the punching a
* buffer head at a time.
*/
STATIC void
xfs_aops_discard_page(
struct page *page)
{
struct inode *inode = page->mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct buffer_head *bh, *head;
loff_t offset = page_offset(page);
if (!xfs_check_page_type(page, XFS_IO_DELALLOC, true))
goto out_invalidate;
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
goto out_invalidate;
xfs_alert(ip->i_mount,
"page discard on page %p, inode 0x%llx, offset %llu.",
page, ip->i_ino, offset);
xfs_ilock(ip, XFS_ILOCK_EXCL);
bh = head = page_buffers(page);
do {
int error;
xfs_fileoff_t start_fsb;
if (!buffer_delay(bh))
goto next_buffer;
start_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
error = xfs_bmap_punch_delalloc_range(ip, start_fsb, 1);
if (error) {
/* something screwed, just bail */
if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
xfs_alert(ip->i_mount,
"page discard unable to remove delalloc mapping.");
}
break;
}
next_buffer:
offset += 1 << inode->i_blkbits;
} while ((bh = bh->b_this_page) != head);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
out_invalidate:
xfs_vm_invalidatepage(page, 0, PAGE_CACHE_SIZE);
return;
}
static int
xfs_writepage_submit(
struct xfs_ioend *ioend,
struct xfs_ioend *iohead,
struct writeback_control *wbc,
int status)
{
struct blk_plug plug;
/* Reserve log space if we might write beyond the on-disk inode size. */
if (!status && ioend && ioend->io_type != XFS_IO_UNWRITTEN &&
xfs_ioend_is_append(ioend))
status = xfs_setfilesize_trans_alloc(ioend);
if (iohead) {
blk_start_plug(&plug);
xfs_submit_ioend(wbc, iohead, status);
blk_finish_plug(&plug);
}
return status;
}
/*
* 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.
* For any other dirty buffer heads on the page we should flush them.
*/
STATIC int
xfs_vm_writepage(
struct page *page,
struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
struct buffer_head *bh, *head;
struct xfs_bmbt_irec imap;
xfs_ioend_t *ioend = NULL, *iohead = NULL;
loff_t offset;
unsigned int type;
__uint64_t end_offset;
pgoff_t end_index, last_index;
ssize_t len;
int err, imap_valid = 0, uptodate = 1;
int count = 0;
trace_xfs_writepage(inode, page, 0, 0);
ASSERT(page_has_buffers(page));
/*
* 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;
/*
* Given that we do not allow direct reclaim to call us, we should
* never be called while in a filesystem transaction.
*/
if (WARN_ON_ONCE(current->flags & PF_FSTRANS))
goto redirty;
/* Is this page beyond the end of the file? */
offset = i_size_read(inode);
end_index = offset >> PAGE_CACHE_SHIFT;
last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
/*
* 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 |
* ---------------------------------^------------------|
*/
if (page->index < end_index)
end_offset = (xfs_off_t)(page->index + 1) << PAGE_CACHE_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_CACHE_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
* xfs_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_CACHE_SIZE);
/* Adjust the end_offset to the end of file */
end_offset = offset;
}
len = 1 << inode->i_blkbits;
bh = head = page_buffers(page);
offset = page_offset(page);
type = XFS_IO_OVERWRITE;
do {
int new_ioend = 0;
if (offset >= end_offset)
break;
if (!buffer_uptodate(bh))
uptodate = 0;
/*
* set_page_dirty dirties all buffers in a page, independent
* of their state. The dirty state however is entirely
* meaningless for holes (!mapped && uptodate), so skip
* buffers covering holes here.
*/
if (!buffer_mapped(bh) && buffer_uptodate(bh)) {
imap_valid = 0;
continue;
}
if (buffer_unwritten(bh)) {
if (type != XFS_IO_UNWRITTEN) {
type = XFS_IO_UNWRITTEN;
imap_valid = 0;
}
} else if (buffer_delay(bh)) {
if (type != XFS_IO_DELALLOC) {
type = XFS_IO_DELALLOC;
imap_valid = 0;
}
} else if (buffer_uptodate(bh)) {
if (type != XFS_IO_OVERWRITE) {
type = XFS_IO_OVERWRITE;
imap_valid = 0;
}
} else {
if (PageUptodate(page))
ASSERT(buffer_mapped(bh));
/*
* This buffer is not uptodate and will not be
* written to disk. Ensure that we will put any
* subsequent writeable buffers into a new
* ioend.
*/
imap_valid = 0;
continue;
}
if (imap_valid)
imap_valid = xfs_imap_valid(inode, &imap, offset);
if (!imap_valid) {
/*
* If we didn't have a valid mapping then we need to
* put the new mapping into a separate ioend structure.
* This ensures non-contiguous extents always have
* separate ioends, which is particularly important
* for unwritten extent conversion at I/O completion
* time.
*/
new_ioend = 1;
err = xfs_map_blocks(inode, offset, &imap, type);
if (err)
goto error;
imap_valid = xfs_imap_valid(inode, &imap, offset);
}
if (imap_valid) {
lock_buffer(bh);
if (type != XFS_IO_OVERWRITE)
xfs_map_at_offset(inode, bh, &imap, offset);
xfs_add_to_ioend(inode, bh, offset, type, &ioend,
new_ioend);
count++;
}
if (!iohead)
iohead = ioend;
} while (offset += len, ((bh = bh->b_this_page) != head));
if (uptodate && bh == head)
SetPageUptodate(page);
xfs_start_page_writeback(page, 1, count);
/* if there is no IO to be submitted for this page, we are done */
if (!ioend)
return 0;
ASSERT(iohead);
ASSERT(err == 0);
/*
* Any errors from this point onwards need tobe reported through the IO
* completion path as we have marked the initial page as under writeback
* and unlocked it.
*/
if (imap_valid) {
xfs_off_t end_index;
end_index = imap.br_startoff + imap.br_blockcount;
/* to bytes */
end_index <<= inode->i_blkbits;
/* to pages */
end_index = (end_index - 1) >> PAGE_CACHE_SHIFT;
/* check against file size */
if (end_index > last_index)
end_index = last_index;
xfs_cluster_write(inode, page->index + 1, &imap, &ioend,
wbc, end_index);
}
return xfs_writepage_submit(ioend, iohead, wbc, 0);
error:
/*
* On error, we have to fail the iohead here because we buffers locked
* in the ioend chain. If we don't do this, we'll deadlock invalidating
* the page as that tries to lock the buffers on the page. Also, because
* we may have set pages under writeback, we have to run IO completion to
* mark the error state of the IO appropriately, so we can't cancel the
* ioend directly here. That means we have to mark this page as under
* writeback if we included any buffers from it in the ioend chain.
*/
if (count)
xfs_start_page_writeback(page, 0, count);
xfs_writepage_submit(ioend, iohead, wbc, err);
/*
* We can only discard the page we had the IO error on if we haven't
* included it in the ioend above. If it has already been errored out,
* the it is unlocked and we can't touch it here.
*/
if (!count) {
xfs_aops_discard_page(page);
ClearPageUptodate(page);
unlock_page(page);
}
mapping_set_error(page->mapping, err);
return err;
redirty:
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
STATIC int
xfs_vm_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
return generic_writepages(mapping, wbc);
}
/*
* Called to move a page into cleanable state - and from there
* to be released. The page should already be clean. We always
* have buffer heads in this call.
*
* Returns 1 if the page is ok to release, 0 otherwise.
*/
STATIC int
xfs_vm_releasepage(
struct page *page,
gfp_t gfp_mask)
{
int delalloc, unwritten;
trace_xfs_releasepage(page->mapping->host, page, 0, 0);
xfs_count_page_state(page, &delalloc, &unwritten);
if (WARN_ON_ONCE(delalloc))
return 0;
if (WARN_ON_ONCE(unwritten))
return 0;
return try_to_free_buffers(page);
}
/*
* When we map a DIO buffer, we may need to attach an ioend that describes the
* type of write IO we are doing. This passes to the completion function the
* operations it needs to perform. If the mapping is for an overwrite wholly
* within the EOF then we don't need an ioend and so we don't allocate one.
* This avoids the unnecessary overhead of allocating and freeing ioends for
* workloads that don't require transactions on IO completion.
*
* If we get multiple mappings in a single IO, we might be mapping different
* types. But because the direct IO can only have a single private pointer, we
* need to ensure that:
*
* a) i) the ioend spans the entire region of unwritten mappings; or
* ii) the ioend spans all the mappings that cross or are beyond EOF; and
* b) if it contains unwritten extents, it is *permanently* marked as such
*
* We could do this by chaining ioends like buffered IO does, but we only
* actually get one IO completion callback from the direct IO, and that spans
* the entire IO regardless of how many mappings and IOs are needed to complete
* the DIO. There is only going to be one reference to the ioend and its life
* cycle is constrained by the DIO completion code. hence we don't need
* reference counting here.
*
* Note that for DIO, an IO to the highest supported file block offset (i.e.
* 2^63 - 1FSB bytes) will result in the offset + count overflowing a signed 64
* bit variable. Hence if we see this overflow, we have to assume that the IO is
* extending the file size. We won't know for sure until IO completion is run
* and the actual max write offset is communicated to the IO completion
* routine.
*
* For DAX page faults, we are preparing to never see unwritten extents here,
* nor should we ever extend the inode size. Hence we will soon have nothing to
* do here for this case, ensuring we don't have to provide an IO completion
* callback to free an ioend that we don't actually need for a fault into the
* page at offset (2^63 - 1FSB) bytes.
*/
static void
xfs_map_direct(
struct inode *inode,
struct buffer_head *bh_result,
struct xfs_bmbt_irec *imap,
xfs_off_t offset,
bool dax_fault)
{
struct xfs_ioend *ioend;
xfs_off_t size = bh_result->b_size;
int type;
if (ISUNWRITTEN(imap))
type = XFS_IO_UNWRITTEN;
else
type = XFS_IO_OVERWRITE;
trace_xfs_gbmap_direct(XFS_I(inode), offset, size, type, imap);
if (dax_fault) {
ASSERT(type == XFS_IO_OVERWRITE);
trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type,
imap);
return;
}
if (bh_result->b_private) {
ioend = bh_result->b_private;
ASSERT(ioend->io_size > 0);
ASSERT(offset >= ioend->io_offset);
if (offset + size > ioend->io_offset + ioend->io_size)
ioend->io_size = offset - ioend->io_offset + size;
if (type == XFS_IO_UNWRITTEN && type != ioend->io_type)
ioend->io_type = XFS_IO_UNWRITTEN;
trace_xfs_gbmap_direct_update(XFS_I(inode), ioend->io_offset,
ioend->io_size, ioend->io_type,
imap);
} else if (type == XFS_IO_UNWRITTEN ||
offset + size > i_size_read(inode) ||
offset + size < 0) {
ioend = xfs_alloc_ioend(inode, type);
ioend->io_offset = offset;
ioend->io_size = size;
bh_result->b_private = ioend;
set_buffer_defer_completion(bh_result);
trace_xfs_gbmap_direct_new(XFS_I(inode), offset, size, type,
imap);
} else {
trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type,
imap);
}
}
/*
* If this is O_DIRECT or the mpage code calling tell them how large the mapping
* is, so that we can avoid repeated get_blocks calls.
*
* If the mapping spans EOF, then we have to break the mapping up as the mapping
* for blocks beyond EOF must be marked new so that sub block regions can be
* correctly zeroed. We can't do this for mappings within EOF unless the mapping
* was just allocated or is unwritten, otherwise the callers would overwrite
* existing data with zeros. Hence we have to split the mapping into a range up
* to and including EOF, and a second mapping for beyond EOF.
*/
static void
xfs_map_trim_size(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
struct xfs_bmbt_irec *imap,
xfs_off_t offset,
ssize_t size)
{
xfs_off_t mapping_size;
mapping_size = imap->br_startoff + imap->br_blockcount - iblock;
mapping_size <<= inode->i_blkbits;
ASSERT(mapping_size > 0);
if (mapping_size > size)
mapping_size = size;
if (offset < i_size_read(inode) &&
offset + mapping_size >= i_size_read(inode)) {
/* limit mapping to block that spans EOF */
mapping_size = roundup_64(i_size_read(inode) - offset,
1 << inode->i_blkbits);
}
if (mapping_size > LONG_MAX)
mapping_size = LONG_MAX;
bh_result->b_size = mapping_size;
}
STATIC int
__xfs_get_blocks(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
int create,
bool direct,
bool dax_fault)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
xfs_fileoff_t offset_fsb, end_fsb;
int error = 0;
int lockmode = 0;
struct xfs_bmbt_irec imap;
int nimaps = 1;
xfs_off_t offset;
ssize_t size;
int new = 0;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
offset = (xfs_off_t)iblock << inode->i_blkbits;
ASSERT(bh_result->b_size >= (1 << inode->i_blkbits));
size = bh_result->b_size;
if (!create && direct && offset >= i_size_read(inode))
return 0;
/*
* Direct I/O is usually done on preallocated files, so try getting
* a block mapping without an exclusive lock first. For buffered
* writes we already have the exclusive iolock anyway, so avoiding
* a lock roundtrip here by taking the ilock exclusive from the
* beginning is a useful micro optimization.
*/
if (create && !direct) {
lockmode = XFS_ILOCK_EXCL;
xfs_ilock(ip, lockmode);
} else {
lockmode = xfs_ilock_data_map_shared(ip);
}
ASSERT(offset <= mp->m_super->s_maxbytes);
if (offset + size > mp->m_super->s_maxbytes)
size = mp->m_super->s_maxbytes - offset;
end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
&imap, &nimaps, XFS_BMAPI_ENTIRE);
if (error)
goto out_unlock;
/* for DAX, we convert unwritten extents directly */
if (create &&
(!nimaps ||
(imap.br_startblock == HOLESTARTBLOCK ||
imap.br_startblock == DELAYSTARTBLOCK) ||
(IS_DAX(inode) && ISUNWRITTEN(&imap)))) {
if (direct || xfs_get_extsz_hint(ip)) {
/*
* xfs_iomap_write_direct() expects the shared lock. It
* is unlocked on return.
*/
if (lockmode == XFS_ILOCK_EXCL)
xfs_ilock_demote(ip, lockmode);
error = xfs_iomap_write_direct(ip, offset, size,
&imap, nimaps);
if (error)
return error;
new = 1;
} else {
/*
* Delalloc reservations do not require a transaction,
* we can go on without dropping the lock here. If we
* are allocating a new delalloc block, make sure that
* we set the new flag so that we mark the buffer new so
* that we know that it is newly allocated if the write
* fails.
*/
if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
new = 1;
error = xfs_iomap_write_delay(ip, offset, size, &imap);
if (error)
goto out_unlock;
xfs_iunlock(ip, lockmode);
}
trace_xfs_get_blocks_alloc(ip, offset, size,
ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN
: XFS_IO_DELALLOC, &imap);
} else if (nimaps) {
trace_xfs_get_blocks_found(ip, offset, size,
ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN
: XFS_IO_OVERWRITE, &imap);
xfs_iunlock(ip, lockmode);
} else {
trace_xfs_get_blocks_notfound(ip, offset, size);
goto out_unlock;
}
if (IS_DAX(inode) && create) {
ASSERT(!ISUNWRITTEN(&imap));
/* zeroing is not needed at a higher layer */
new = 0;
}
/* trim mapping down to size requested */
if (direct || size > (1 << inode->i_blkbits))
xfs_map_trim_size(inode, iblock, bh_result,
&imap, offset, size);
/*
* For unwritten extents do not report a disk address in the buffered
* read case (treat as if we're reading into a hole).
*/
if (imap.br_startblock != HOLESTARTBLOCK &&
imap.br_startblock != DELAYSTARTBLOCK &&
(create || !ISUNWRITTEN(&imap))) {
xfs_map_buffer(inode, bh_result, &imap, offset);
if (ISUNWRITTEN(&imap))
set_buffer_unwritten(bh_result);
/* direct IO needs special help */
if (create && direct)
xfs_map_direct(inode, bh_result, &imap, offset,
dax_fault);
}
/*
* If this is a realtime file, data may be on a different device.
* to that pointed to from the buffer_head b_bdev currently.
*/
bh_result->b_bdev = xfs_find_bdev_for_inode(inode);
/*
* If we previously allocated a block out beyond eof and we are now
* coming back to use it then we will need to flag it as new even if it
* has a disk address.
*
* With sub-block writes into unwritten extents we also need to mark
* the buffer as new so that the unwritten parts of the buffer gets
* correctly zeroed.
*/
if (create &&
((!buffer_mapped(bh_result) && !buffer_uptodate(bh_result)) ||
(offset >= i_size_read(inode)) ||
(new || ISUNWRITTEN(&imap))))
set_buffer_new(bh_result);
if (imap.br_startblock == DELAYSTARTBLOCK) {
BUG_ON(direct);
if (create) {
set_buffer_uptodate(bh_result);
set_buffer_mapped(bh_result);
set_buffer_delay(bh_result);
}
}
return 0;
out_unlock:
xfs_iunlock(ip, lockmode);
return error;
}
int
xfs_get_blocks(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
int create)
{
return __xfs_get_blocks(inode, iblock, bh_result, create, false, false);
}
int
xfs_get_blocks_direct(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
int create)
{
return __xfs_get_blocks(inode, iblock, bh_result, create, true, false);
}
int
xfs_get_blocks_dax_fault(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
int create)
{
return __xfs_get_blocks(inode, iblock, bh_result, create, true, true);
}
static void
__xfs_end_io_direct_write(
struct inode *inode,
struct xfs_ioend *ioend,
loff_t offset,
ssize_t size)
{
struct xfs_mount *mp = XFS_I(inode)->i_mount;
if (XFS_FORCED_SHUTDOWN(mp) || ioend->io_error)
goto out_end_io;
/*
* dio completion end_io functions are only called on writes if more
* than 0 bytes was written.
*/
ASSERT(size > 0);
/*
* The ioend only maps whole blocks, while the IO may be sector aligned.
* Hence the ioend offset/size may not match the IO offset/size exactly.
* Because we don't map overwrites within EOF into the ioend, the offset
* may not match, but only if the endio spans EOF. Either way, write
* the IO sizes into the ioend so that completion processing does the
* right thing.
*/
ASSERT(offset + size <= ioend->io_offset + ioend->io_size);
ioend->io_size = size;
ioend->io_offset = offset;
/*
* The ioend tells us whether we are doing unwritten extent conversion
* or an append transaction that updates the on-disk file size. These
* cases are the only cases where we should *potentially* be needing
* to update the VFS inode size.
*
* We need to update the in-core inode size here so that we don't end up
* with the on-disk inode size being outside the in-core inode size. We
* have no other method of updating EOF for AIO, so always do it here
* if necessary.
*
* We need to lock the test/set EOF update as we can be racing with
* other IO completions here to update the EOF. Failing to serialise
* here can result in EOF moving backwards and Bad Things Happen when
* that occurs.
*/
spin_lock(&XFS_I(inode)->i_flags_lock);
if (offset + size > i_size_read(inode))
i_size_write(inode, offset + size);
spin_unlock(&XFS_I(inode)->i_flags_lock);
/*
* If we are doing an append IO that needs to update the EOF on disk,
* do the transaction reserve now so we can use common end io
* processing. Stashing the error (if there is one) in the ioend will
* result in the ioend processing passing on the error if it is
* possible as we can't return it from here.
*/
if (ioend->io_type == XFS_IO_OVERWRITE)
ioend->io_error = xfs_setfilesize_trans_alloc(ioend);
out_end_io:
xfs_end_io(&ioend->io_work);
return;
}
/*
* Complete a direct I/O write request.
*
* The ioend structure is passed from __xfs_get_blocks() to tell us what to do.
* If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite
* wholly within the EOF and so there is nothing for us to do. Note that in this
* case the completion can be called in interrupt context, whereas if we have an
* ioend we will always be called in task context (i.e. from a workqueue).
*/
STATIC void
xfs_end_io_direct_write(
struct kiocb *iocb,
loff_t offset,
ssize_t size,
void *private)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct xfs_ioend *ioend = private;
trace_xfs_gbmap_direct_endio(XFS_I(inode), offset, size,
ioend ? ioend->io_type : 0, NULL);
if (!ioend) {
ASSERT(offset + size <= i_size_read(inode));
return;
}
__xfs_end_io_direct_write(inode, ioend, offset, size);
}
static inline ssize_t
xfs_vm_do_dio(
struct inode *inode,
struct kiocb *iocb,
struct iov_iter *iter,
loff_t offset,
void (*endio)(struct kiocb *iocb,
loff_t offset,
ssize_t size,
void *private),
int flags)
{
struct block_device *bdev;
if (IS_DAX(inode))
return dax_do_io(iocb, inode, iter, offset,
xfs_get_blocks_direct, endio, 0);
bdev = xfs_find_bdev_for_inode(inode);
return __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
xfs_get_blocks_direct, endio, NULL, flags);
}
STATIC ssize_t
xfs_vm_direct_IO(
struct kiocb *iocb,
struct iov_iter *iter,
loff_t offset)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
if (iov_iter_rw(iter) == WRITE)
return xfs_vm_do_dio(inode, iocb, iter, offset,
xfs_end_io_direct_write, DIO_ASYNC_EXTEND);
return xfs_vm_do_dio(inode, iocb, iter, offset, NULL, 0);
}
/*
* Punch out the delalloc blocks we have already allocated.
*
* Don't bother with xfs_setattr given that nothing can have made it to disk yet
* as the page is still locked at this point.
*/
STATIC void
xfs_vm_kill_delalloc_range(
struct inode *inode,
loff_t start,
loff_t end)
{
struct xfs_inode *ip = XFS_I(inode);
xfs_fileoff_t start_fsb;
xfs_fileoff_t end_fsb;
int error;
start_fsb = XFS_B_TO_FSB(ip->i_mount, start);
end_fsb = XFS_B_TO_FSB(ip->i_mount, end);
if (end_fsb <= start_fsb)
return;
xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
end_fsb - start_fsb);
if (error) {
/* something screwed, just bail */
if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
xfs_alert(ip->i_mount,
"xfs_vm_write_failed: unable to clean up ino %lld",
ip->i_ino);
}
}
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
STATIC void
xfs_vm_write_failed(
struct inode *inode,
struct page *page,
loff_t pos,
unsigned len)
{
loff_t block_offset;
loff_t block_start;
loff_t block_end;
loff_t from = pos & (PAGE_CACHE_SIZE - 1);
loff_t to = from + len;
struct buffer_head *bh, *head;
/*
* The request pos offset might be 32 or 64 bit, this is all fine
* on 64-bit platform. However, for 64-bit pos request on 32-bit
* platform, the high 32-bit will be masked off if we evaluate the
* block_offset via (pos & PAGE_MASK) because the PAGE_MASK is
* 0xfffff000 as an unsigned long, hence the result is incorrect
* which could cause the following ASSERT failed in most cases.
* In order to avoid this, we can evaluate the block_offset of the
* start of the page by using shifts rather than masks the mismatch
* problem.
*/
block_offset = (pos >> PAGE_CACHE_SHIFT) << PAGE_CACHE_SHIFT;
ASSERT(block_offset + from == pos);
head = page_buffers(page);
block_start = 0;
for (bh = head; bh != head || !block_start;
bh = bh->b_this_page, block_start = block_end,
block_offset += bh->b_size) {
block_end = block_start + bh->b_size;
/* skip buffers before the write */
if (block_end <= from)
continue;
/* if the buffer is after the write, we're done */
if (block_start >= to)
break;
if (!buffer_delay(bh))
continue;
if (!buffer_new(bh) && block_offset < i_size_read(inode))
continue;
xfs_vm_kill_delalloc_range(inode, block_offset,
block_offset + bh->b_size);
/*
* This buffer does not contain data anymore. make sure anyone
* who finds it knows that for certain.
*/
clear_buffer_delay(bh);
clear_buffer_uptodate(bh);
clear_buffer_mapped(bh);
clear_buffer_new(bh);
clear_buffer_dirty(bh);
}
}
/*
* This used to call block_write_begin(), but it unlocks and releases the page
* on error, and we need that page to be able to punch stale delalloc blocks out
* on failure. hence we copy-n-waste it here and call xfs_vm_write_failed() at
* the appropriate point.
*/
STATIC int
xfs_vm_write_begin(
struct file *file,
struct address_space *mapping,
loff_t pos,
unsigned len,
unsigned flags,
struct page **pagep,
void **fsdata)
{
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
struct page *page;
int status;
ASSERT(len <= PAGE_CACHE_SIZE);
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
status = __block_write_begin(page, pos, len, xfs_get_blocks);
if (unlikely(status)) {
struct inode *inode = mapping->host;
size_t isize = i_size_read(inode);
xfs_vm_write_failed(inode, page, pos, len);
unlock_page(page);
/*
* If the write is beyond EOF, we only want to kill blocks
* allocated in this write, not blocks that were previously
* written successfully.
*/
if (pos + len > isize) {
ssize_t start = max_t(ssize_t, pos, isize);
truncate_pagecache_range(inode, start, pos + len);
}
page_cache_release(page);
page = NULL;
}
*pagep = page;
return status;
}
/*
* On failure, we only need to kill delalloc blocks beyond EOF in the range of
* this specific write because they will never be written. Previous writes
* beyond EOF where block allocation succeeded do not need to be trashed, so
* only new blocks from this write should be trashed. For blocks within
* EOF, generic_write_end() zeros them so they are safe to leave alone and be
* written with all the other valid data.
*/
STATIC int
xfs_vm_write_end(
struct file *file,
struct address_space *mapping,
loff_t pos,
unsigned len,
unsigned copied,
struct page *page,
void *fsdata)
{
int ret;
ASSERT(len <= PAGE_CACHE_SIZE);
ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
if (unlikely(ret < len)) {
struct inode *inode = mapping->host;
size_t isize = i_size_read(inode);
loff_t to = pos + len;
if (to > isize) {
/* only kill blocks in this write beyond EOF */
if (pos > isize)
isize = pos;
xfs_vm_kill_delalloc_range(inode, isize, to);
truncate_pagecache_range(inode, isize, to);
}
}
return ret;
}
STATIC sector_t
xfs_vm_bmap(
struct address_space *mapping,
sector_t block)
{
struct inode *inode = (struct inode *)mapping->host;
struct xfs_inode *ip = XFS_I(inode);
trace_xfs_vm_bmap(XFS_I(inode));
xfs_ilock(ip, XFS_IOLOCK_SHARED);
filemap_write_and_wait(mapping);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
return generic_block_bmap(mapping, block, xfs_get_blocks);
}
STATIC int
xfs_vm_readpage(
struct file *unused,
struct page *page)
{
trace_xfs_vm_readpage(page->mapping->host, 1);
return mpage_readpage(page, xfs_get_blocks);
}
STATIC int
xfs_vm_readpages(
struct file *unused,
struct address_space *mapping,
struct list_head *pages,
unsigned nr_pages)
{
trace_xfs_vm_readpages(mapping->host, nr_pages);
return mpage_readpages(mapping, pages, nr_pages, xfs_get_blocks);
}
/*
* This is basically a copy of __set_page_dirty_buffers() with one
* small tweak: buffers beyond EOF do not get marked dirty. If we mark them
* dirty, we'll never be able to clean them because we don't write buffers
* beyond EOF, and that means we can't invalidate pages that span EOF
* that have been marked dirty. Further, the dirty state can leak into
* the file interior if the file is extended, resulting in all sorts of
* bad things happening as the state does not match the underlying data.
*
* XXX: this really indicates that bufferheads in XFS need to die. Warts like
* this only exist because of bufferheads and how the generic code manages them.
*/
STATIC int
xfs_vm_set_page_dirty(
struct page *page)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
loff_t end_offset;
loff_t offset;
int newly_dirty;
struct mem_cgroup *memcg;
if (unlikely(!mapping))
return !TestSetPageDirty(page);
end_offset = i_size_read(inode);
offset = page_offset(page);
spin_lock(&mapping->private_lock);
if (page_has_buffers(page)) {
struct buffer_head *head = page_buffers(page);
struct buffer_head *bh = head;
do {
if (offset < end_offset)
set_buffer_dirty(bh);
bh = bh->b_this_page;
offset += 1 << inode->i_blkbits;
} while (bh != head);
}
/*
* Use mem_group_begin_page_stat() to keep PageDirty synchronized with
* per-memcg dirty page counters.
*/
memcg = mem_cgroup_begin_page_stat(page);
newly_dirty = !TestSetPageDirty(page);
spin_unlock(&mapping->private_lock);
if (newly_dirty) {
/* sigh - __set_page_dirty() is static, so copy it here, too */
unsigned long flags;
spin_lock_irqsave(&mapping->tree_lock, flags);
if (page->mapping) { /* Race with truncate? */
WARN_ON_ONCE(!PageUptodate(page));
account_page_dirtied(page, mapping, memcg);
radix_tree_tag_set(&mapping->page_tree,
page_index(page), PAGECACHE_TAG_DIRTY);
}
spin_unlock_irqrestore(&mapping->tree_lock, flags);
}
mem_cgroup_end_page_stat(memcg);
if (newly_dirty)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
return newly_dirty;
}
const struct address_space_operations xfs_address_space_operations = {
.readpage = xfs_vm_readpage,
.readpages = xfs_vm_readpages,
.writepage = xfs_vm_writepage,
.writepages = xfs_vm_writepages,
.set_page_dirty = xfs_vm_set_page_dirty,
.releasepage = xfs_vm_releasepage,
.invalidatepage = xfs_vm_invalidatepage,
.write_begin = xfs_vm_write_begin,
.write_end = xfs_vm_write_end,
.bmap = xfs_vm_bmap,
.direct_IO = xfs_vm_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
};