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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) 2016-2018 Christoph Hellwig.
* All Rights Reserved.
*/
#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_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_quota.h"
#include "xfs_dquot_item.h"
#include "xfs_dquot.h"
#include "xfs_reflink.h"
#define XFS_ALLOC_ALIGN(mp, off) \
(((off) >> mp->m_allocsize_log) << mp->m_allocsize_log)
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_bmbt_to_iomap(
struct xfs_inode *ip,
struct iomap *iomap,
struct xfs_bmbt_irec *imap,
u16 flags)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_buftarg *target = xfs_inode_buftarg(ip);
if (unlikely(!xfs_valid_startblock(ip, imap->br_startblock)))
return xfs_alert_fsblock_zero(ip, imap);
if (imap->br_startblock == HOLESTARTBLOCK) {
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_HOLE;
} else if (imap->br_startblock == DELAYSTARTBLOCK ||
isnullstartblock(imap->br_startblock)) {
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 = target->bt_bdev;
iomap->dax_dev = target->bt_daxdev;
iomap->flags = flags;
if (xfs_ipincount(ip) &&
(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
iomap->flags |= IOMAP_F_DIRTY;
return 0;
}
static void
xfs_hole_to_iomap(
struct xfs_inode *ip,
struct iomap *iomap,
xfs_fileoff_t offset_fsb,
xfs_fileoff_t end_fsb)
{
struct xfs_buftarg *target = xfs_inode_buftarg(ip);
iomap->addr = IOMAP_NULL_ADDR;
iomap->type = IOMAP_HOLE;
iomap->offset = XFS_FSB_TO_B(ip->i_mount, offset_fsb);
iomap->length = XFS_FSB_TO_B(ip->i_mount, end_fsb - offset_fsb);
iomap->bdev = target->bt_bdev;
iomap->dax_dev = target->bt_daxdev;
}
static inline xfs_fileoff_t
xfs_iomap_end_fsb(
struct xfs_mount *mp,
loff_t offset,
loff_t count)
{
ASSERT(offset <= mp->m_super->s_maxbytes);
return min(XFS_B_TO_FSB(mp, offset + count),
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
}
static xfs_extlen_t
xfs_eof_alignment(
struct xfs_inode *ip)
{
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;
}
return align;
}
/*
* Check if last_fsb is outside the last extent, and if so grow it to the next
* stripe unit boundary.
*/
xfs_fileoff_t
xfs_iomap_eof_align_last_fsb(
struct xfs_inode *ip,
xfs_fileoff_t end_fsb)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
xfs_extlen_t extsz = xfs_get_extsz_hint(ip);
xfs_extlen_t align = xfs_eof_alignment(ip);
struct xfs_bmbt_irec irec;
struct xfs_iext_cursor icur;
ASSERT(ifp->if_flags & XFS_IFEXTENTS);
/*
* Always round up the allocation request to the extent hint boundary.
*/
if (extsz) {
if (align)
align = roundup_64(align, extsz);
else
align = extsz;
}
if (align) {
xfs_fileoff_t aligned_end_fsb = roundup_64(end_fsb, align);
xfs_iext_last(ifp, &icur);
if (!xfs_iext_get_extent(ifp, &icur, &irec) ||
aligned_end_fsb >= irec.br_startoff + irec.br_blockcount)
return aligned_end_fsb;
}
return end_fsb;
}
int
xfs_iomap_write_direct(
struct xfs_inode *ip,
xfs_fileoff_t offset_fsb,
xfs_fileoff_t count_fsb,
struct xfs_bmbt_irec *imap)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
xfs_filblks_t resaligned;
int nimaps;
int quota_flag;
uint qblocks, resblks;
unsigned int resrtextents = 0;
int error;
int bmapi_flags = XFS_BMAPI_PREALLOC;
uint tflags = 0;
ASSERT(count_fsb > 0);
resaligned = xfs_aligned_fsb_count(offset_fsb, count_fsb,
xfs_get_extsz_hint(ip));
if (unlikely(XFS_IS_REALTIME_INODE(ip))) {
resrtextents = qblocks = resaligned;
resrtextents /= mp->m_sb.sb_rextsize;
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
quota_flag = XFS_QMOPT_RES_RTBLKS;
} else {
resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
quota_flag = XFS_QMOPT_RES_REGBLKS;
}
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;
xfs_ilock(ip, XFS_ILOCK_EXCL);
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.
*/
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flags, 0,
imap, &nimaps);
if (error)
goto out_res_cancel;
/*
* Complete the transaction
*/
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 (unlikely(!xfs_valid_startblock(ip, imap->br_startblock)))
error = xfs_alert_fsblock_zero(ip, imap);
out_unlock:
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
out_res_cancel:
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,
xfs_dqtype_t 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_blk.reserved + alloc_blocks < dq->q_prealloc_lo_wmark)
return false;
return true;
}
STATIC void
xfs_quota_calc_throttle(
struct xfs_inode *ip,
xfs_dqtype_t type,
xfs_fsblock_t *qblocks,
int *qshift,
int64_t *qfreesp)
{
struct xfs_dquot *dq = xfs_inode_dquot(ip, type);
int64_t freesp;
int shift = 0;
/* no dq, or over hi wmark, squash the prealloc completely */
if (!dq || dq->q_blk.reserved >= dq->q_prealloc_hi_wmark) {
*qblocks = 0;
*qfreesp = 0;
return;
}
freesp = dq->q_prealloc_hi_wmark - dq->q_blk.reserved;
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 being full, the smaller the maximum preallocation.
*/
STATIC xfs_fsblock_t
xfs_iomap_prealloc_size(
struct xfs_inode *ip,
int whichfork,
loff_t offset,
loff_t count,
struct xfs_iext_cursor *icur)
{
struct xfs_iext_cursor ncur = *icur;
struct xfs_bmbt_irec prev, got;
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
int64_t freesp;
xfs_fsblock_t qblocks;
xfs_fsblock_t alloc_blocks = 0;
xfs_extlen_t plen;
int shift = 0;
int qshift = 0;
/*
* 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.
*/
if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks))
return 0;
/*
* Use the minimum preallocation size for small files or if we are
* writing right after a hole.
*/
if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
!xfs_iext_prev_extent(ifp, &ncur, &prev) ||
prev.br_startoff + prev.br_blockcount < offset_fsb)
return mp->m_allocsize_blocks;
/*
* Take the size of the preceding data extents as the basis for the
* preallocation size. Note that we don't care if the previous extents
* are written or not.
*/
plen = prev.br_blockcount;
while (xfs_iext_prev_extent(ifp, &ncur, &got)) {
if (plen > MAXEXTLEN / 2 ||
isnullstartblock(got.br_startblock) ||
got.br_startoff + got.br_blockcount != prev.br_startoff ||
got.br_startblock + got.br_blockcount != prev.br_startblock)
break;
plen += got.br_blockcount;
prev = got;
}
/*
* If the size of the extents 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.
*/
alloc_blocks = plen * 2;
if (alloc_blocks > MAXEXTLEN)
alloc_blocks = XFS_B_TO_FSB(mp, offset);
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_DQTYPE_USER, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQTYPE_USER, &qblocks, &qshift,
&freesp);
if (xfs_quota_need_throttle(ip, XFS_DQTYPE_GROUP, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQTYPE_GROUP, &qblocks, &qshift,
&freesp);
if (xfs_quota_need_throttle(ip, XFS_DQTYPE_PROJ, alloc_blocks))
xfs_quota_calc_throttle(ip, XFS_DQTYPE_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;
if (alloc_blocks < mp->m_allocsize_blocks)
alloc_blocks = mp->m_allocsize_blocks;
trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
mp->m_allocsize_blocks);
return alloc_blocks;
}
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;
int nimaps;
xfs_trans_t *tp;
xfs_bmbt_irec_t imap;
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;
/* Attach dquots so that bmbt splits are accounted correctly. */
error = xfs_qm_dqattach(ip);
if (error)
return error;
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, &tp);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);
error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES);
if (error)
goto error_on_bmapi_transaction;
/*
* Modify the unwritten extent state of the buffer.
*/
nimaps = 1;
error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
XFS_BMAPI_CONVERT, resblks, &imap,
&nimaps);
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_trans_commit(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
if (unlikely(!xfs_valid_startblock(ip, imap.br_startblock)))
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_trans_cancel(tp);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
return error;
}
static inline bool
imap_needs_alloc(
struct inode *inode,
unsigned flags,
struct xfs_bmbt_irec *imap,
int nimaps)
{
/* don't allocate blocks when just zeroing */
if (flags & IOMAP_ZERO)
return false;
if (!nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_startblock == DELAYSTARTBLOCK)
return true;
/* we convert unwritten extents before copying the data for DAX */
if (IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN)
return true;
return false;
}
static inline bool
imap_needs_cow(
struct xfs_inode *ip,
unsigned int flags,
struct xfs_bmbt_irec *imap,
int nimaps)
{
if (!xfs_is_cow_inode(ip))
return false;
/* when zeroing we don't have to COW holes or unwritten extents */
if (flags & IOMAP_ZERO) {
if (!nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_state == XFS_EXT_UNWRITTEN)
return false;
}
return true;
}
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_cow_inode(ip) && is_write)
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);
}
/*
* The reflink iflag could have changed since the earlier unlocked
* check, so if we got ILOCK_SHARED for a write and but we're now a
* reflink inode we have to switch to ILOCK_EXCL and relock.
*/
if (mode == XFS_ILOCK_SHARED && is_write && xfs_is_cow_inode(ip)) {
xfs_iunlock(ip, mode);
mode = XFS_ILOCK_EXCL;
goto relock;
}
*lockmode = mode;
return 0;
}
static int
xfs_direct_write_iomap_begin(
struct inode *inode,
loff_t offset,
loff_t length,
unsigned flags,
struct iomap *iomap,
struct iomap *srcmap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_bmbt_irec imap, cmap;
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = xfs_iomap_end_fsb(mp, offset, length);
int nimaps = 1, error = 0;
bool shared = false;
u16 iomap_flags = 0;
unsigned lockmode;
ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO));
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
/*
* Writes that span EOF might trigger an IO size update on completion,
* so consider them to be dirty for the purposes of O_DSYNC even if
* there is no other metadata changes pending or have been made here.
*/
if (offset + length > i_size_read(inode))
iomap_flags |= IOMAP_F_DIRTY;
error = xfs_ilock_for_iomap(ip, flags, &lockmode);
if (error)
return error;
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
&nimaps, 0);
if (error)
goto out_unlock;
if (imap_needs_cow(ip, flags, &imap, nimaps)) {
error = -EAGAIN;
if (flags & IOMAP_NOWAIT)
goto out_unlock;
/* may drop and re-acquire the ilock */
error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
&lockmode, flags & IOMAP_DIRECT);
if (error)
goto out_unlock;
if (shared)
goto out_found_cow;
end_fsb = imap.br_startoff + imap.br_blockcount;
length = XFS_FSB_TO_B(mp, end_fsb) - offset;
}
if (imap_needs_alloc(inode, flags, &imap, nimaps))
goto allocate_blocks;
xfs_iunlock(ip, lockmode);
trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags);
allocate_blocks:
error = -EAGAIN;
if (flags & IOMAP_NOWAIT)
goto out_unlock;
/*
* We cap the maximum length we map to a sane size 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.
*/
length = min_t(loff_t, length, 1024 * PAGE_SIZE);
end_fsb = xfs_iomap_end_fsb(mp, offset, length);
if (offset + length > XFS_ISIZE(ip))
end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
end_fsb = min(end_fsb, imap.br_startoff + imap.br_blockcount);
xfs_iunlock(ip, lockmode);
error = xfs_iomap_write_direct(ip, offset_fsb, end_fsb - offset_fsb,
&imap);
if (error)
return error;
trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap);
return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags | IOMAP_F_NEW);
out_found_cow:
xfs_iunlock(ip, lockmode);
length = XFS_FSB_TO_B(mp, cmap.br_startoff + cmap.br_blockcount);
trace_xfs_iomap_found(ip, offset, length - offset, XFS_COW_FORK, &cmap);
if (imap.br_startblock != HOLESTARTBLOCK) {
error = xfs_bmbt_to_iomap(ip, srcmap, &imap, 0);
if (error)
return error;
}
return xfs_bmbt_to_iomap(ip, iomap, &cmap, IOMAP_F_SHARED);
out_unlock:
xfs_iunlock(ip, lockmode);
return error;
}
const struct iomap_ops xfs_direct_write_iomap_ops = {
.iomap_begin = xfs_direct_write_iomap_begin,
};
static int
xfs_buffered_write_iomap_begin(
struct inode *inode,
loff_t offset,
loff_t count,
unsigned flags,
struct iomap *iomap,
struct iomap *srcmap)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = xfs_iomap_end_fsb(mp, offset, count);
struct xfs_bmbt_irec imap, cmap;
struct xfs_iext_cursor icur, ccur;
xfs_fsblock_t prealloc_blocks = 0;
bool eof = false, cow_eof = false, shared = false;
int allocfork = XFS_DATA_FORK;
int error = 0;
/* we can't use delayed allocations when using extent size hints */
if (xfs_get_extsz_hint(ip))
return xfs_direct_write_iomap_begin(inode, offset, count,
flags, iomap, srcmap);
ASSERT(!XFS_IS_REALTIME_INODE(ip));
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(&ip->i_df)) ||
XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
error = -EFSCORRUPTED;
goto out_unlock;
}
XFS_STATS_INC(mp, xs_blk_mapw);
if (!(ip->i_df.if_flags & XFS_IFEXTENTS)) {
error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
if (error)
goto out_unlock;
}
/*
* Search the data fork first to look up our source mapping. We
* always need the data fork map, as we have to return it to the
* iomap code so that the higher level write code can read data in to
* perform read-modify-write cycles for unaligned writes.
*/
eof = !xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap);
if (eof)
imap.br_startoff = end_fsb; /* fake hole until the end */
/* We never need to allocate blocks for zeroing a hole. */
if ((flags & IOMAP_ZERO) && imap.br_startoff > offset_fsb) {
xfs_hole_to_iomap(ip, iomap, offset_fsb, imap.br_startoff);
goto out_unlock;
}
/*
* Search the COW fork extent list even if we did not find a data fork
* extent. This serves two purposes: first this implements the
* speculative preallocation using cowextsize, so that we also unshare
* block adjacent to shared blocks instead of just the shared blocks
* themselves. Second the lookup in the extent list is generally faster
* than going out to the shared extent tree.
*/
if (xfs_is_cow_inode(ip)) {
if (!ip->i_cowfp) {
ASSERT(!xfs_is_reflink_inode(ip));
xfs_ifork_init_cow(ip);
}
cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb,
&ccur, &cmap);
if (!cow_eof && cmap.br_startoff <= offset_fsb) {
trace_xfs_reflink_cow_found(ip, &cmap);
goto found_cow;
}
}
if (imap.br_startoff <= offset_fsb) {
/*
* For reflink files we may need a delalloc reservation when
* overwriting shared extents. This includes zeroing of
* existing extents that contain data.
*/
if (!xfs_is_cow_inode(ip) ||
((flags & IOMAP_ZERO) && imap.br_state != XFS_EXT_NORM)) {
trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
&imap);
goto found_imap;
}
xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
/* Trim the mapping to the nearest shared extent boundary. */
error = xfs_bmap_trim_cow(ip, &imap, &shared);
if (error)
goto out_unlock;
/* Not shared? Just report the (potentially capped) extent. */
if (!shared) {
trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
&imap);
goto found_imap;
}
/*
* Fork all the shared blocks from our write offset until the
* end of the extent.
*/
allocfork = XFS_COW_FORK;
end_fsb = imap.br_startoff + imap.br_blockcount;
} else {
/*
* 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.
*
* 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 = xfs_iomap_end_fsb(mp, offset, count);
if (xfs_is_always_cow_inode(ip))
allocfork = XFS_COW_FORK;
}
error = xfs_qm_dqattach_locked(ip, false);
if (error)
goto out_unlock;
if (eof && offset + count > XFS_ISIZE(ip)) {
/*
* Determine the initial size of the preallocation.
* We clean up any extra preallocation when the file is closed.
*/
if (mp->m_flags & XFS_MOUNT_ALLOCSIZE)
prealloc_blocks = mp->m_allocsize_blocks;
else
prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork,
offset, count, &icur);
if (prealloc_blocks) {
xfs_extlen_t align;
xfs_off_t end_offset;
xfs_fileoff_t p_end_fsb;
end_offset = XFS_ALLOC_ALIGN(mp, offset + count - 1);
p_end_fsb = XFS_B_TO_FSBT(mp, end_offset) +
prealloc_blocks;
align = xfs_eof_alignment(ip);
if (align)
p_end_fsb = roundup_64(p_end_fsb, align);
p_end_fsb = min(p_end_fsb,
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
ASSERT(p_end_fsb > offset_fsb);
prealloc_blocks = p_end_fsb - end_fsb;
}
}
retry:
error = xfs_bmapi_reserve_delalloc(ip, allocfork, offset_fsb,
end_fsb - offset_fsb, prealloc_blocks,
allocfork == XFS_DATA_FORK ? &imap : &cmap,
allocfork == XFS_DATA_FORK ? &icur : &ccur,
allocfork == XFS_DATA_FORK ? eof : cow_eof);
switch (error) {
case 0:
break;
case -ENOSPC:
case -EDQUOT:
/* retry without any preallocation */
trace_xfs_delalloc_enospc(ip, offset, count);