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xfs_iomap.c
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xfs_iomap.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* Copyright (c) 2016 Christoph Hellwig.
* All Rights Reserved.
*/
#include <linux/iomap.h>
#include "xfs.h"
#include "xfs_fs.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_defer.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_inode_item.h"
#include "xfs_iomap.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_quota.h"
#include "xfs_dquot_item.h"
#include "xfs_dquot.h"
#include "xfs_reflink.h"
#define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \
<< mp->m_writeio_log)
void
xfs_bmbt_to_iomap(
struct xfs_inode *ip,
struct iomap *iomap,
struct xfs_bmbt_irec *imap)
{
struct xfs_mount *mp = ip->i_mount;
if (imap->br_startblock == HOLESTARTBLOCK) {
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_HOLE;
} else if (imap->br_startblock == DELAYSTARTBLOCK) {
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_DELALLOC;
} else {
iomap->addr = BBTOB(xfs_fsb_to_db(ip, imap->br_startblock));
if (imap->br_state == XFS_EXT_UNWRITTEN)
iomap->type = IOMAP_UNWRITTEN;
else
iomap->type = IOMAP_MAPPED;
}
iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
iomap->bdev = xfs_find_bdev_for_inode(VFS_I(ip));
iomap->dax_dev = xfs_find_daxdev_for_inode(VFS_I(ip));
}
xfs_extlen_t
xfs_eof_alignment(
struct xfs_inode *ip,
xfs_extlen_t extsize)
{
struct xfs_mount *mp = ip->i_mount;
xfs_extlen_t align = 0;
if (!XFS_IS_REALTIME_INODE(ip)) {
/*
* Round up the allocation request to a stripe unit
* (m_dalign) boundary if the file size is >= stripe unit
* size, and we are allocating past the allocation eof.
*
* If mounted with the "-o swalloc" option the alignment is
* increased from the strip unit size to the stripe width.
*/
if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
align = mp->m_swidth;
else if (mp->m_dalign)
align = mp->m_dalign;
if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align))
align = 0;
}
/*
* Always round up the allocation request to an extent boundary
* (when file on a real-time subvolume or has di_extsize hint).
*/
if (extsize) {
if (align)
align = roundup_64(align, extsize);
else
align = extsize;
}
return align;
}
STATIC int
xfs_iomap_eof_align_last_fsb(
struct xfs_inode *ip,
xfs_extlen_t extsize,
xfs_fileoff_t *last_fsb)
{
xfs_extlen_t align = xfs_eof_alignment(ip, extsize);
if (align) {
xfs_fileoff_t new_last_fsb = roundup_64(*last_fsb, align);
int eof, error;
error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
if (error)
return error;
if (eof)
*last_fsb = new_last_fsb;
}
return 0;
}
STATIC int
xfs_alert_fsblock_zero(
xfs_inode_t *ip,
xfs_bmbt_irec_t *imap)
{
xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
"Access to block zero in inode %llu "
"start_block: %llx start_off: %llx "
"blkcnt: %llx extent-state: %x",
(unsigned long long)ip->i_ino,
(unsigned long long)imap->br_startblock,
(unsigned long long)imap->br_startoff,
(unsigned long long)imap->br_blockcount,
imap->br_state);
return -EFSCORRUPTED;
}
int
xfs_iomap_write_direct(
xfs_inode_t *ip,
xfs_off_t offset,
size_t count,
xfs_bmbt_irec_t *imap,
int nmaps)
{
xfs_mount_t *mp = ip->i_mount;
xfs_fileoff_t offset_fsb;
xfs_fileoff_t last_fsb;
xfs_filblks_t count_fsb, resaligned;
xfs_fsblock_t firstfsb;
xfs_extlen_t extsz;
int nimaps;
int quota_flag;
int rt;
xfs_trans_t *tp;
struct xfs_defer_ops dfops;
uint qblocks, resblks, resrtextents;
int error;
int lockmode;
int bmapi_flags = XFS_BMAPI_PREALLOC;
uint tflags = 0;
rt = XFS_IS_REALTIME_INODE(ip);
extsz = xfs_get_extsz_hint(ip);
lockmode = XFS_ILOCK_SHARED; /* locked by caller */
ASSERT(xfs_isilocked(ip, lockmode));
offset_fsb = XFS_B_TO_FSBT(mp, offset);
last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
if ((offset + count) > XFS_ISIZE(ip)) {
/*
* Assert that the in-core extent list is present since this can
* call xfs_iread_extents() and we only have the ilock shared.
* This should be safe because the lock was held around a bmapi
* call in the caller and we only need it to access the in-core
* list.
*/
ASSERT(XFS_IFORK_PTR(ip, XFS_DATA_FORK)->if_flags &
XFS_IFEXTENTS);
error = xfs_iomap_eof_align_last_fsb(ip, extsz, &last_fsb);
if (error)
goto out_unlock;
} else {
if (nmaps && (imap->br_startblock == HOLESTARTBLOCK))
last_fsb = min(last_fsb, (xfs_fileoff_t)
imap->br_blockcount +
imap->br_startoff);
}
count_fsb = last_fsb - offset_fsb;
ASSERT(count_fsb > 0);
resaligned = xfs_aligned_fsb_count(offset_fsb, count_fsb, extsz);
if (unlikely(rt)) {
resrtextents = qblocks = resaligned;
resrtextents /= mp->m_sb.sb_rextsize;
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
quota_flag = XFS_QMOPT_RES_RTBLKS;
} else {
resrtextents = 0;
resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
quota_flag = XFS_QMOPT_RES_REGBLKS;
}
/*
* Drop the shared lock acquired by the caller, attach the dquot if
* necessary and move on to transaction setup.
*/
xfs_iunlock(ip, lockmode);
error = xfs_qm_dqattach(ip);
if (error)
return error;
/*
* For DAX, we do not allocate unwritten extents, but instead we zero
* the block before we commit the transaction. Ideally we'd like to do
* this outside the transaction context, but if we commit and then crash
* we may not have zeroed the blocks and this will be exposed on
* recovery of the allocation. Hence we must zero before commit.
*
* Further, if we are mapping unwritten extents here, we need to zero
* and convert them to written so that we don't need an unwritten extent
* callback for DAX. This also means that we need to be able to dip into
* the reserve block pool for bmbt block allocation if there is no space
* left but we need to do unwritten extent conversion.
*/
if (IS_DAX(VFS_I(ip))) {
bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO;
if (imap->br_state == XFS_EXT_UNWRITTEN) {
tflags |= XFS_TRANS_RESERVE;
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
}
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, resrtextents,
tflags, &tp);
if (error)
return error;
lockmode = XFS_ILOCK_EXCL;
xfs_ilock(ip, lockmode);
error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
if (error)
goto out_trans_cancel;
xfs_trans_ijoin(tp, ip, 0);
/*
* From this point onwards we overwrite the imap pointer that the
* caller gave to us.
*/
xfs_defer_init(&dfops, &firstfsb);
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
bmapi_flags, &firstfsb, resblks, imap,
&nimaps, &dfops);
if (error)
goto out_bmap_cancel;
/*
* Complete the transaction
*/
error = xfs_defer_finish(&tp, &dfops);
if (error)
goto out_bmap_cancel;
error = xfs_trans_commit(tp);
if (error)
goto out_unlock;
/*
* Copy any maps to caller's array and return any error.
*/
if (nimaps == 0) {
error = -ENOSPC;
goto out_unlock;
}
if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
error = xfs_alert_fsblock_zero(ip, imap);
out_unlock:
xfs_iunlock(ip, lockmode);
return error;
out_bmap_cancel:
xfs_defer_cancel(&dfops);
xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
out_trans_cancel:
xfs_trans_cancel(tp);
goto out_unlock;
}
STATIC bool
xfs_quota_need_throttle(
struct xfs_inode *ip,
int type,
xfs_fsblock_t alloc_blocks)
{
struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
if (!dq || !xfs_this_quota_on(ip->i_mount, type))
return false;
/* no hi watermark, no throttle */
if (!dq->q_prealloc_hi_wmark)
return false;
/* under the lo watermark, no throttle */
if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark)
return false;
return true;
}
STATIC void
xfs_quota_calc_throttle(
struct xfs_inode *ip,
int type,
xfs_fsblock_t *qblocks,
int *qshift,
int64_t *qfreesp)
{
int64_t freesp;
int shift = 0;
struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
/* no dq, or over hi wmark, squash the prealloc completely */
if (!dq || dq->q_res_bcount >= dq->q_prealloc_hi_wmark) {
*qblocks = 0;
*qfreesp = 0;
return;
}
freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount;
if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) {
shift = 2;
if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT])
shift += 2;
if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT])
shift += 2;
}
if (freesp < *qfreesp)
*qfreesp = freesp;
/* only overwrite the throttle values if we are more aggressive */
if ((freesp >> shift) < (*qblocks >> *qshift)) {
*qblocks = freesp;
*qshift = shift;
}
}
/*
* If we are doing a write at the end of the file and there are no allocations
* past this one, then extend the allocation out to the file system's write
* iosize.
*
* If we don't have a user specified preallocation size, dynamically increase
* the preallocation size as the size of the file grows. Cap the maximum size
* at a single extent or less if the filesystem is near full. The closer the
* filesystem is to full, the smaller the maximum prealocation.
*
* As an exception we don't do any preallocation at all if the file is smaller
* than the minimum preallocation and we are using the default dynamic
* preallocation scheme, as it is likely this is the only write to the file that
* is going to be done.
*
* We clean up any extra space left over when the file is closed in
* xfs_inactive().
*/
STATIC xfs_fsblock_t
xfs_iomap_prealloc_size(
struct xfs_inode *ip,
loff_t offset,
loff_t count,
struct xfs_iext_cursor *icur)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
struct xfs_bmbt_irec prev;
int shift = 0;
int64_t freesp;
xfs_fsblock_t qblocks;
int qshift = 0;
xfs_fsblock_t alloc_blocks = 0;
if (offset + count <= XFS_ISIZE(ip))
return 0;
if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
(XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks)))
return 0;
/*
* If an explicit allocsize is set, the file is small, or we
* are writing behind a hole, then use the minimum prealloc:
*/
if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
!xfs_iext_peek_prev_extent(ifp, icur, &prev) ||
prev.br_startoff + prev.br_blockcount < offset_fsb)
return mp->m_writeio_blocks;
/*
* Determine the initial size of the preallocation. We are beyond the
* current EOF here, but we need to take into account whether this is
* a sparse write or an extending write when determining the
* preallocation size. Hence we need to look up the extent that ends
* at the current write offset and use the result to determine the
* preallocation size.
*
* If the extent is a hole, then preallocation is essentially disabled.
* Otherwise we take the size of the preceding data extent as the basis
* for the preallocation size. If the size of the extent is greater than
* half the maximum extent length, then use the current offset as the
* basis. This ensures that for large files the preallocation size
* always extends to MAXEXTLEN rather than falling short due to things
* like stripe unit/width alignment of real extents.
*/
if (prev.br_blockcount <= (MAXEXTLEN >> 1))
alloc_blocks = prev.br_blockcount << 1;
else
alloc_blocks = XFS_B_TO_FSB(mp, offset);
if (!alloc_blocks)
goto check_writeio;
qblocks = alloc_blocks;
/*
* MAXEXTLEN is not a power of two value but we round the prealloc down
* to the nearest power of two value after throttling. To prevent the
* round down from unconditionally reducing the maximum supported prealloc
* size, we round up first, apply appropriate throttling, round down and
* cap the value to MAXEXTLEN.
*/
alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN),
alloc_blocks);
freesp = percpu_counter_read_positive(&mp->m_fdblocks);
if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) {
shift = 2;
if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT])
shift++;
if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT])
shift++;
if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT])
shift++;
if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT])
shift++;
}
/*
* Check each quota to cap the prealloc size, provide a shift value to
* throttle with and adjust amount of available space.
*/
if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift,
&freesp);
if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift,
&freesp);
if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift,
&freesp);
/*
* The final prealloc size is set to the minimum of free space available
* in each of the quotas and the overall filesystem.
*
* The shift throttle value is set to the maximum value as determined by
* the global low free space values and per-quota low free space values.
*/
alloc_blocks = min(alloc_blocks, qblocks);
shift = max(shift, qshift);
if (shift)
alloc_blocks >>= shift;
/*
* rounddown_pow_of_two() returns an undefined result if we pass in
* alloc_blocks = 0.
*/
if (alloc_blocks)
alloc_blocks = rounddown_pow_of_two(alloc_blocks);
if (alloc_blocks > MAXEXTLEN)
alloc_blocks = MAXEXTLEN;
/*
* If we are still trying to allocate more space than is
* available, squash the prealloc hard. This can happen if we
* have a large file on a small filesystem and the above
* lowspace thresholds are smaller than MAXEXTLEN.
*/
while (alloc_blocks && alloc_blocks >= freesp)
alloc_blocks >>= 4;
check_writeio:
if (alloc_blocks < mp->m_writeio_blocks)
alloc_blocks = mp->m_writeio_blocks;
trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
mp->m_writeio_blocks);
return alloc_blocks;
}
static int
xfs_file_iomap_begin_delay(
struct inode *inode,
loff_t offset,
loff_t count,
struct iomap *iomap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t maxbytes_fsb =
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
xfs_fileoff_t end_fsb;
int error = 0, eof = 0;
struct xfs_bmbt_irec got;
struct xfs_iext_cursor icur;
xfs_fsblock_t prealloc_blocks = 0;
ASSERT(!XFS_IS_REALTIME_INODE(ip));
ASSERT(!xfs_get_extsz_hint(ip));
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (unlikely(XFS_TEST_ERROR(
(XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_EXTENTS &&
XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_BTREE),
mp, XFS_ERRTAG_BMAPIFORMAT))) {
XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
error = -EFSCORRUPTED;
goto out_unlock;
}
XFS_STATS_INC(mp, xs_blk_mapw);
if (!(ifp->if_flags & XFS_IFEXTENTS)) {
error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
if (error)
goto out_unlock;
}
eof = !xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got);
if (!eof && got.br_startoff <= offset_fsb) {
if (xfs_is_reflink_inode(ip)) {
bool shared;
end_fsb = min(XFS_B_TO_FSB(mp, offset + count),
maxbytes_fsb);
xfs_trim_extent(&got, offset_fsb, end_fsb - offset_fsb);
error = xfs_reflink_reserve_cow(ip, &got, &shared);
if (error)
goto out_unlock;
}
trace_xfs_iomap_found(ip, offset, count, 0, &got);
goto done;
}
error = xfs_qm_dqattach_locked(ip, false);
if (error)
goto out_unlock;
/*
* We cap the maximum length we map here to MAX_WRITEBACK_PAGES pages
* to keep the chunks of work done where somewhat symmetric with the
* work writeback does. This is a completely arbitrary number pulled
* out of thin air as a best guess for initial testing.
*
* Note that the values needs to be less than 32-bits wide until
* the lower level functions are updated.
*/
count = min_t(loff_t, count, 1024 * PAGE_SIZE);
end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
if (eof) {
prealloc_blocks = xfs_iomap_prealloc_size(ip, offset, count,
&icur);
if (prealloc_blocks) {
xfs_extlen_t align;
xfs_off_t end_offset;
xfs_fileoff_t p_end_fsb;
end_offset = XFS_WRITEIO_ALIGN(mp, offset + count - 1);
p_end_fsb = XFS_B_TO_FSBT(mp, end_offset) +
prealloc_blocks;
align = xfs_eof_alignment(ip, 0);
if (align)
p_end_fsb = roundup_64(p_end_fsb, align);
p_end_fsb = min(p_end_fsb, maxbytes_fsb);
ASSERT(p_end_fsb > offset_fsb);
prealloc_blocks = p_end_fsb - end_fsb;
}
}
retry:
error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
end_fsb - offset_fsb, prealloc_blocks, &got, &icur,
eof);
switch (error) {
case 0:
break;
case -ENOSPC:
case -EDQUOT:
/* retry without any preallocation */
trace_xfs_delalloc_enospc(ip, offset, count);
if (prealloc_blocks) {
prealloc_blocks = 0;
goto retry;
}
/*FALLTHRU*/
default:
goto out_unlock;
}
/*
* Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
* them out if the write happens to fail.
*/
iomap->flags = IOMAP_F_NEW;
trace_xfs_iomap_alloc(ip, offset, count, 0, &got);
done:
if (isnullstartblock(got.br_startblock))
got.br_startblock = DELAYSTARTBLOCK;
if (!got.br_startblock) {
error = xfs_alert_fsblock_zero(ip, &got);
if (error)
goto out_unlock;
}
xfs_bmbt_to_iomap(ip, iomap, &got);
out_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}
/*
* Pass in a delayed allocate extent, convert it to real extents;
* return to the caller the extent we create which maps on top of
* the originating callers request.
*
* Called without a lock on the inode.
*
* We no longer bother to look at the incoming map - all we have to
* guarantee is that whatever we allocate fills the required range.
*/
int
xfs_iomap_write_allocate(
xfs_inode_t *ip,
int whichfork,
xfs_off_t offset,
xfs_bmbt_irec_t *imap)
{
xfs_mount_t *mp = ip->i_mount;
xfs_fileoff_t offset_fsb, last_block;
xfs_fileoff_t end_fsb, map_start_fsb;
xfs_fsblock_t first_block;
struct xfs_defer_ops dfops;
xfs_filblks_t count_fsb;
xfs_trans_t *tp;
int nimaps;
int error = 0;
int flags = XFS_BMAPI_DELALLOC;
int nres;
if (whichfork == XFS_COW_FORK)
flags |= XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC;
/*
* Make sure that the dquots are there.
*/
error = xfs_qm_dqattach(ip);
if (error)
return error;
offset_fsb = XFS_B_TO_FSBT(mp, offset);
count_fsb = imap->br_blockcount;
map_start_fsb = imap->br_startoff;
XFS_STATS_ADD(mp, xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb));
while (count_fsb != 0) {
/*
* Set up a transaction with which to allocate the
* backing store for the file. Do allocations in a
* loop until we get some space in the range we are
* interested in. The other space that might be allocated
* is in the delayed allocation extent on which we sit
* but before our buffer starts.
*/
nimaps = 0;
while (nimaps == 0) {
nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
/*
* We have already reserved space for the extent and any
* indirect blocks when creating the delalloc extent,
* there is no need to reserve space in this transaction
* again.
*/
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0,
0, XFS_TRANS_RESERVE, &tp);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
xfs_defer_init(&dfops, &first_block);
/*
* it is possible that the extents have changed since
* we did the read call as we dropped the ilock for a
* while. We have to be careful about truncates or hole
* punchs here - we are not allowed to allocate
* non-delalloc blocks here.
*
* The only protection against truncation is the pages
* for the range we are being asked to convert are
* locked and hence a truncate will block on them
* first.
*
* As a result, if we go beyond the range we really
* need and hit an delalloc extent boundary followed by
* a hole while we have excess blocks in the map, we
* will fill the hole incorrectly and overrun the
* transaction reservation.
*
* Using a single map prevents this as we are forced to
* check each map we look for overlap with the desired
* range and abort as soon as we find it. Also, given
* that we only return a single map, having one beyond
* what we can return is probably a bit silly.
*
* We also need to check that we don't go beyond EOF;
* this is a truncate optimisation as a truncate sets
* the new file size before block on the pages we
* currently have locked under writeback. Because they
* are about to be tossed, we don't need to write them
* back....
*/
nimaps = 1;
end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
error = xfs_bmap_last_offset(ip, &last_block,
XFS_DATA_FORK);
if (error)
goto trans_cancel;
last_block = XFS_FILEOFF_MAX(last_block, end_fsb);
if ((map_start_fsb + count_fsb) > last_block) {
count_fsb = last_block - map_start_fsb;
if (count_fsb == 0) {
error = -EAGAIN;
goto trans_cancel;
}
}
/*
* From this point onwards we overwrite the imap
* pointer that the caller gave to us.
*/
error = xfs_bmapi_write(tp, ip, map_start_fsb,
count_fsb, flags, &first_block,
nres, imap, &nimaps,
&dfops);
if (error)
goto trans_cancel;
error = xfs_defer_finish(&tp, &dfops);
if (error)
goto trans_cancel;
error = xfs_trans_commit(tp);
if (error)
goto error0;
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
/*
* See if we were able to allocate an extent that
* covers at least part of the callers request
*/
if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip)))
return xfs_alert_fsblock_zero(ip, imap);
if ((offset_fsb >= imap->br_startoff) &&
(offset_fsb < (imap->br_startoff +
imap->br_blockcount))) {
XFS_STATS_INC(mp, xs_xstrat_quick);
return 0;
}
/*
* So far we have not mapped the requested part of the
* file, just surrounding data, try again.
*/
count_fsb -= imap->br_blockcount;
map_start_fsb = imap->br_startoff + imap->br_blockcount;
}
trans_cancel:
xfs_defer_cancel(&dfops);
xfs_trans_cancel(tp);
error0:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}
int
xfs_iomap_write_unwritten(
xfs_inode_t *ip,
xfs_off_t offset,
xfs_off_t count,
bool update_isize)
{
xfs_mount_t *mp = ip->i_mount;
xfs_fileoff_t offset_fsb;
xfs_filblks_t count_fsb;
xfs_filblks_t numblks_fsb;
xfs_fsblock_t firstfsb;
int nimaps;
xfs_trans_t *tp;
xfs_bmbt_irec_t imap;
struct xfs_defer_ops dfops;
struct inode *inode = VFS_I(ip);
xfs_fsize_t i_size;
uint resblks;
int error;
trace_xfs_unwritten_convert(ip, offset, count);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
/*
* Reserve enough blocks in this transaction for two complete extent
* btree splits. We may be converting the middle part of an unwritten
* extent and in this case we will insert two new extents in the btree
* each of which could cause a full split.
*
* This reservation amount will be used in the first call to
* xfs_bmbt_split() to select an AG with enough space to satisfy the
* rest of the operation.
*/
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
do {
/*
* Set up a transaction to convert the range of extents
* from unwritten to real. Do allocations in a loop until
* we have covered the range passed in.
*
* Note that we can't risk to recursing back into the filesystem
* here as we might be asked to write out the same inode that we
* complete here and might deadlock on the iolock.
*/
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
/*
* Modify the unwritten extent state of the buffer.
*/
xfs_defer_init(&dfops, &firstfsb);
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
XFS_BMAPI_CONVERT, &firstfsb, resblks,
&imap, &nimaps, &dfops);
if (error)
goto error_on_bmapi_transaction;
/*
* Log the updated inode size as we go. We have to be careful
* to only log it up to the actual write offset if it is
* halfway into a block.
*/
i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
if (i_size > offset + count)
i_size = offset + count;
if (update_isize && i_size > i_size_read(inode))
i_size_write(inode, i_size);
i_size = xfs_new_eof(ip, i_size);
if (i_size) {
ip->i_d.di_size = i_size;
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
}
error = xfs_defer_finish(&tp, &dfops);
if (error)
goto error_on_bmapi_transaction;
error = xfs_trans_commit(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip)))
return xfs_alert_fsblock_zero(ip, &imap);
if ((numblks_fsb = imap.br_blockcount) == 0) {
/*
* The numblks_fsb value should always get
* smaller, otherwise the loop is stuck.
*/
ASSERT(imap.br_blockcount);
break;
}
offset_fsb += numblks_fsb;
count_fsb -= numblks_fsb;
} while (count_fsb > 0);
return 0;
error_on_bmapi_transaction:
xfs_defer_cancel(&dfops);
xfs_trans_cancel(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}
static inline bool
imap_needs_alloc(
struct inode *inode,
struct xfs_bmbt_irec *imap,
int nimaps)
{
return !nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_startblock == DELAYSTARTBLOCK ||
(IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);
}
static inline bool
needs_cow_for_zeroing(
struct xfs_bmbt_irec *imap,
int nimaps)
{
return nimaps &&
imap->br_startblock != HOLESTARTBLOCK &&
imap->br_state != XFS_EXT_UNWRITTEN;
}
static int
xfs_ilock_for_iomap(
struct xfs_inode *ip,
unsigned flags,
unsigned *lockmode)
{
unsigned mode = XFS_ILOCK_SHARED;
bool is_write = flags & (IOMAP_WRITE | IOMAP_ZERO);
/*
* COW writes may allocate delalloc space or convert unwritten COW
* extents, so we need to make sure to take the lock exclusively here.
*/
if (xfs_is_reflink_inode(ip) && is_write) {
/*
* FIXME: It could still overwrite on unshared extents and not
* need allocation.
*/
if (flags & IOMAP_NOWAIT)
return -EAGAIN;
mode = XFS_ILOCK_EXCL;
}
/*
* Extents not yet cached requires exclusive access, don't block. This
* is an opencoded xfs_ilock_data_map_shared() call but with
* non-blocking behaviour.
*/
if (!(ip->i_df.if_flags & XFS_IFEXTENTS)) {
if (flags & IOMAP_NOWAIT)
return -EAGAIN;
mode = XFS_ILOCK_EXCL;
}
relock:
if (flags & IOMAP_NOWAIT) {
if (!xfs_ilock_nowait(ip, mode))
return -EAGAIN;
} else {
xfs_ilock(ip, mode);
}