- 根目录:
- fs
- xfs
- xfs_iomap.c
/*
* Copyright (c) 2000-2006 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_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_inode.h"
#include "xfs_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_error.h"
#include "xfs_trans.h"
#include "xfs_trans_space.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"
#define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \
<< mp->m_writeio_log)
#define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP
STATIC int
xfs_iomap_eof_align_last_fsb(
xfs_mount_t *mp,
xfs_inode_t *ip,
xfs_extlen_t extsize,
xfs_fileoff_t *last_fsb)
{
xfs_extlen_t align = 0;
int eof, error;
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;
}
if (align) {
xfs_fileoff_t new_last_fsb = roundup_64(*last_fsb, align);
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, temp;
int nimaps;
int quota_flag;
int rt;
xfs_trans_t *tp;
xfs_bmap_free_t free_list;
uint qblocks, resblks, resrtextents;
int committed;
int error;
int lockmode;
int bmapi_flags = XFS_BMAPI_PREALLOC;
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(mp, 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 = count_fsb;
if (unlikely(extsz)) {
if ((temp = do_mod(offset_fsb, extsz)))
resaligned += temp;
if ((temp = do_mod(resaligned, extsz)))
resaligned += extsz - temp;
}
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, 0);
if (error)
return error;
/*
* Allocate and setup the transaction
*/
tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
/*
* 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 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;
tp->t_flags |= XFS_TRANS_RESERVE;
}
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
resblks, resrtextents);
/*
* Check for running out of space, note: need lock to return
*/
if (error) {
xfs_trans_cancel(tp);
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_bmap_init(&free_list, &firstfsb);
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
bmapi_flags, &firstfsb, resblks, imap,
&nimaps, &free_list);
if (error)
goto out_bmap_cancel;
/*
* Complete the transaction
*/
error = xfs_bmap_finish(&tp, &free_list, &committed);
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_bmap_cancel(&free_list);
xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
out_trans_cancel:
xfs_trans_cancel(tp);
goto out_unlock;
}
/*
* If the caller is doing a write at the end of the file, then extend the
* allocation out to the file system's write iosize. We clean up any extra
* space left over when the file is closed in xfs_inactive().
*
* If we find we already have delalloc preallocation beyond EOF, don't do more
* preallocation as it it not needed.
*/
STATIC int
xfs_iomap_eof_want_preallocate(
xfs_mount_t *mp,
xfs_inode_t *ip,
xfs_off_t offset,
size_t count,
xfs_bmbt_irec_t *imap,
int nimaps,
int *prealloc)
{
xfs_fileoff_t start_fsb;
xfs_filblks_t count_fsb;
int n, error, imaps;
int found_delalloc = 0;
*prealloc = 0;
if (offset + count <= XFS_ISIZE(ip))
return 0;
/*
* If the file is smaller than the minimum prealloc and we are using
* dynamic preallocation, don't do any preallocation at all as it is
* likely this is the only write to the file that is going to be done.
*/
if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
return 0;
/*
* If there are any real blocks past eof, then don't
* do any speculative allocation.
*/
start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
while (count_fsb > 0) {
imaps = nimaps;
error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
0);
if (error)
return error;
for (n = 0; n < imaps; n++) {
if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
(imap[n].br_startblock != DELAYSTARTBLOCK))
return 0;
start_fsb += imap[n].br_blockcount;
count_fsb -= imap[n].br_blockcount;
if (imap[n].br_startblock == DELAYSTARTBLOCK)
found_delalloc = 1;
}
}
if (!found_delalloc)
*prealloc = 1;
return 0;
}
/*
* 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 preceeding 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.
*/
STATIC xfs_fsblock_t
xfs_iomap_eof_prealloc_initial_size(
struct xfs_mount *mp,
struct xfs_inode *ip,
xfs_off_t offset,
xfs_bmbt_irec_t *imap,
int nimaps)
{
xfs_fileoff_t start_fsb;
int imaps = 1;
int error;
ASSERT(nimaps >= imaps);
/* if we are using a specific prealloc size, return now */
if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
return 0;
/* If the file is small, then use the minimum prealloc */
if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
return 0;
/*
* As we write multiple pages, the offset will always align to the
* start of a page and hence point to a hole at EOF. i.e. if the size is
* 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
* will return FSB 1. Hence if there are blocks in the file, we want to
* point to the block prior to the EOF block and not the hole that maps
* directly at @offset.
*/
start_fsb = XFS_B_TO_FSB(mp, offset);
if (start_fsb)
start_fsb--;
error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
if (error)
return 0;
ASSERT(imaps == 1);
if (imap[0].br_startblock == HOLESTARTBLOCK)
return 0;
if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
return imap[0].br_blockcount << 1;
return XFS_B_TO_FSB(mp, offset);
}
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 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.
*/
STATIC xfs_fsblock_t
xfs_iomap_prealloc_size(
struct xfs_mount *mp,
struct xfs_inode *ip,
xfs_off_t offset,
struct xfs_bmbt_irec *imap,
int nimaps)
{
xfs_fsblock_t alloc_blocks = 0;
int shift = 0;
int64_t freesp;
xfs_fsblock_t qblocks;
int qshift = 0;
alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
imap, nimaps);
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;
}
int
xfs_iomap_write_delay(
xfs_inode_t *ip,
xfs_off_t offset,
size_t count,
xfs_bmbt_irec_t *ret_imap)
{
xfs_mount_t *mp = ip->i_mount;
xfs_fileoff_t offset_fsb;
xfs_fileoff_t last_fsb;
xfs_off_t aligned_offset;
xfs_fileoff_t ioalign;
xfs_extlen_t extsz;
int nimaps;
xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
int prealloc;
int error;
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
/*
* Make sure that the dquots are there. This doesn't hold
* the ilock across a disk read.
*/
error = xfs_qm_dqattach_locked(ip, 0);
if (error)
return error;
extsz = xfs_get_extsz_hint(ip);
offset_fsb = XFS_B_TO_FSBT(mp, offset);
error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
imap, XFS_WRITE_IMAPS, &prealloc);
if (error)
return error;
retry:
if (prealloc) {
xfs_fsblock_t alloc_blocks;
alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
XFS_WRITE_IMAPS);
aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
last_fsb = ioalign + alloc_blocks;
} else {
last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
}
if (prealloc || extsz) {
error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
if (error)
return error;
}
/*
* Make sure preallocation does not create extents beyond the range we
* actually support in this filesystem.
*/
if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
ASSERT(last_fsb > offset_fsb);
nimaps = XFS_WRITE_IMAPS;
error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
imap, &nimaps, XFS_BMAPI_ENTIRE);
switch (error) {
case 0:
case -ENOSPC:
case -EDQUOT:
break;
default:
return error;
}
/*
* If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
* without EOF preallocation.
*/
if (nimaps == 0) {
trace_xfs_delalloc_enospc(ip, offset, count);
if (prealloc) {
prealloc = 0;
error = 0;
goto retry;
}
return error ? error : -ENOSPC;
}
if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
return xfs_alert_fsblock_zero(ip, &imap[0]);
/*
* Tag the inode as speculatively preallocated so we can reclaim this
* space on demand, if necessary.
*/
if (prealloc)
xfs_inode_set_eofblocks_tag(ip);
*ret_imap = imap[0];
return 0;
}
/*
* 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,
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;
xfs_bmap_free_t free_list;
xfs_filblks_t count_fsb;
xfs_trans_t *tp;
int nimaps, committed;
int error = 0;
int nres;
/*
* Make sure that the dquots are there.
*/
error = xfs_qm_dqattach(ip, 0);
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) {
tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE);
tp->t_flags |= XFS_TRANS_RESERVE;
nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
nres, 0);
if (error) {
xfs_trans_cancel(tp);
return error;
}
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
xfs_bmap_init(&free_list, &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, 0, &first_block,
nres, imap, &nimaps,
&free_list);
if (error)
goto trans_cancel;
error = xfs_bmap_finish(&tp, &free_list, &committed);
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_bmap_cancel(&free_list);
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)
{
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;
xfs_bmap_free_t free_list;
xfs_fsize_t i_size;
uint resblks;
int committed;
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 open code the transaction allocation here
* to pass KM_NOFS--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.
*/
sb_start_intwrite(mp->m_super);
tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT;
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
resblks, 0);
if (error) {
xfs_trans_cancel(tp);
return error;
}
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
/*
* Modify the unwritten extent state of the buffer.
*/
xfs_bmap_init(&free_list, &firstfsb);
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
XFS_BMAPI_CONVERT, &firstfsb, resblks,
&imap, &nimaps, &free_list);
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;
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_bmap_finish(&tp, &free_list, &committed);
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_bmap_cancel(&free_list);
xfs_trans_cancel(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}