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linux-stable/fs/xfs/libxfs/xfs_inode_buf.c
Darrick J. Wong 603f000b15 xfs: validate extsz hints against rt extent size when rtinherit is set 
The RTINHERIT bit can be set on a directory so that newly created
regular files will have the REALTIME bit set to store their data on the
realtime volume.  If an extent size hint (and EXTSZINHERIT) are set on
the directory, the hint will also be copied into the new file.

As pointed out in previous patches, for realtime files we require the
extent size hint be an integer multiple of the realtime extent, but we
don't perform the same validation on a directory with both RTINHERIT and
EXTSZINHERIT set, even though the only use-case of that combination is
to propagate extent size hints into new realtime files.  This leads to
inode corruption errors when the bad values are propagated.

Because there may be existing filesystems with such a configuration, we
cannot simply amend the inode verifier to trip on these directories and
call it a day because that will cause previously "working" filesystems
to start throwing errors abruptly.  Note that it's valid to have
directories with rtinherit set even if there is no realtime volume, in
which case the problem does not manifest because rtinherit is ignored if
there's no realtime device; and it's possible that someone set the flag,
crashed, repaired the filesystem (which clears the hint on the realtime
file) and continued.

Therefore, mitigate this issue in several ways: First, if we try to
write out an inode with both rtinherit/extszinherit set and an unaligned
extent size hint, turn off the hint to correct the error.  Second, if
someone tries to misconfigure a directory via the fssetxattr ioctl, fail
the ioctl.  Third, reverify both extent size hint values when we
propagate heritable inode attributes from parent to child, to prevent
misconfigurations from spreading.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
2021-05-24 18:01:04 -07:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* 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_errortag.h"
#include "xfs_error.h"
#include "xfs_icache.h"
#include "xfs_trans.h"
#include "xfs_ialloc.h"
#include "xfs_dir2.h"
#include <linux/iversion.h>
/*
* If we are doing readahead on an inode buffer, we might be in log recovery
* reading an inode allocation buffer that hasn't yet been replayed, and hence
* has not had the inode cores stamped into it. Hence for readahead, the buffer
* may be potentially invalid.
*
* If the readahead buffer is invalid, we need to mark it with an error and
* clear the DONE status of the buffer so that a followup read will re-read it
* from disk. We don't report the error otherwise to avoid warnings during log
* recovery and we don't get unnecessary panics on debug kernels. We use EIO here
* because all we want to do is say readahead failed; there is no-one to report
* the error to, so this will distinguish it from a non-ra verifier failure.
* Changes to this readahead error behaviour also need to be reflected in
* xfs_dquot_buf_readahead_verify().
*/
static void
xfs_inode_buf_verify(
struct xfs_buf *bp,
bool readahead)
{
struct xfs_mount *mp = bp->b_mount;
xfs_agnumber_t agno;
int i;
int ni;
/*
* Validate the magic number and version of every inode in the buffer
*/
agno = xfs_daddr_to_agno(mp, XFS_BUF_ADDR(bp));
ni = XFS_BB_TO_FSB(mp, bp->b_length) * mp->m_sb.sb_inopblock;
for (i = 0; i < ni; i++) {
int di_ok;
xfs_dinode_t *dip;
xfs_agino_t unlinked_ino;
dip = xfs_buf_offset(bp, (i << mp->m_sb.sb_inodelog));
unlinked_ino = be32_to_cpu(dip->di_next_unlinked);
di_ok = xfs_verify_magic16(bp, dip->di_magic) &&
xfs_dinode_good_version(&mp->m_sb, dip->di_version) &&
xfs_verify_agino_or_null(mp, agno, unlinked_ino);
if (unlikely(XFS_TEST_ERROR(!di_ok, mp,
XFS_ERRTAG_ITOBP_INOTOBP))) {
if (readahead) {
bp->b_flags &= ~XBF_DONE;
xfs_buf_ioerror(bp, -EIO);
return;
}
#ifdef DEBUG
xfs_alert(mp,
"bad inode magic/vsn daddr %lld #%d (magic=%x)",
(unsigned long long)bp->b_bn, i,
be16_to_cpu(dip->di_magic));
#endif
xfs_buf_verifier_error(bp, -EFSCORRUPTED,
__func__, dip, sizeof(*dip),
NULL);
return;
}
}
}
static void
xfs_inode_buf_read_verify(
struct xfs_buf *bp)
{
xfs_inode_buf_verify(bp, false);
}
static void
xfs_inode_buf_readahead_verify(
struct xfs_buf *bp)
{
xfs_inode_buf_verify(bp, true);
}
static void
xfs_inode_buf_write_verify(
struct xfs_buf *bp)
{
xfs_inode_buf_verify(bp, false);
}
const struct xfs_buf_ops xfs_inode_buf_ops = {
.name = "xfs_inode",
.magic16 = { cpu_to_be16(XFS_DINODE_MAGIC),
cpu_to_be16(XFS_DINODE_MAGIC) },
.verify_read = xfs_inode_buf_read_verify,
.verify_write = xfs_inode_buf_write_verify,
};
const struct xfs_buf_ops xfs_inode_buf_ra_ops = {
.name = "xfs_inode_ra",
.magic16 = { cpu_to_be16(XFS_DINODE_MAGIC),
cpu_to_be16(XFS_DINODE_MAGIC) },
.verify_read = xfs_inode_buf_readahead_verify,
.verify_write = xfs_inode_buf_write_verify,
};
/*
* This routine is called to map an inode to the buffer containing the on-disk
* version of the inode. It returns a pointer to the buffer containing the
* on-disk inode in the bpp parameter.
*/
int
xfs_imap_to_bp(
struct xfs_mount *mp,
struct xfs_trans *tp,
struct xfs_imap *imap,
struct xfs_buf **bpp)
{
return xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
imap->im_len, XBF_UNMAPPED, bpp,
&xfs_inode_buf_ops);
}
static inline struct timespec64 xfs_inode_decode_bigtime(uint64_t ts)
{
struct timespec64 tv;
uint32_t n;
tv.tv_sec = xfs_bigtime_to_unix(div_u64_rem(ts, NSEC_PER_SEC, &n));
tv.tv_nsec = n;
return tv;
}
/* Convert an ondisk timestamp to an incore timestamp. */
struct timespec64
xfs_inode_from_disk_ts(
struct xfs_dinode *dip,
const xfs_timestamp_t ts)
{
struct timespec64 tv;
struct xfs_legacy_timestamp *lts;
if (xfs_dinode_has_bigtime(dip))
return xfs_inode_decode_bigtime(be64_to_cpu(ts));
lts = (struct xfs_legacy_timestamp *)&ts;
tv.tv_sec = (int)be32_to_cpu(lts->t_sec);
tv.tv_nsec = (int)be32_to_cpu(lts->t_nsec);
return tv;
}
int
xfs_inode_from_disk(
struct xfs_inode *ip,
struct xfs_dinode *from)
{
struct inode *inode = VFS_I(ip);
int error;
xfs_failaddr_t fa;
ASSERT(ip->i_cowfp == NULL);
ASSERT(ip->i_afp == NULL);
fa = xfs_dinode_verify(ip->i_mount, ip->i_ino, from);
if (fa) {
xfs_inode_verifier_error(ip, -EFSCORRUPTED, "dinode", from,
sizeof(*from), fa);
return -EFSCORRUPTED;
}
/*
* First get the permanent information that is needed to allocate an
* inode. If the inode is unused, mode is zero and we shouldn't mess
* with the uninitialized part of it.
*/
if (!xfs_sb_version_has_v3inode(&ip->i_mount->m_sb))
ip->i_flushiter = be16_to_cpu(from->di_flushiter);
inode->i_generation = be32_to_cpu(from->di_gen);
inode->i_mode = be16_to_cpu(from->di_mode);
if (!inode->i_mode)
return 0;
/*
* Convert v1 inodes immediately to v2 inode format as this is the
* minimum inode version format we support in the rest of the code.
* They will also be unconditionally written back to disk as v2 inodes.
*/
if (unlikely(from->di_version == 1)) {
set_nlink(inode, be16_to_cpu(from->di_onlink));
ip->i_projid = 0;
} else {
set_nlink(inode, be32_to_cpu(from->di_nlink));
ip->i_projid = (prid_t)be16_to_cpu(from->di_projid_hi) << 16 |
be16_to_cpu(from->di_projid_lo);
}
i_uid_write(inode, be32_to_cpu(from->di_uid));
i_gid_write(inode, be32_to_cpu(from->di_gid));
/*
* Time is signed, so need to convert to signed 32 bit before
* storing in inode timestamp which may be 64 bit. Otherwise
* a time before epoch is converted to a time long after epoch
* on 64 bit systems.
*/
inode->i_atime = xfs_inode_from_disk_ts(from, from->di_atime);
inode->i_mtime = xfs_inode_from_disk_ts(from, from->di_mtime);
inode->i_ctime = xfs_inode_from_disk_ts(from, from->di_ctime);
ip->i_disk_size = be64_to_cpu(from->di_size);
ip->i_nblocks = be64_to_cpu(from->di_nblocks);
ip->i_extsize = be32_to_cpu(from->di_extsize);
ip->i_forkoff = from->di_forkoff;
ip->i_diflags = be16_to_cpu(from->di_flags);
if (from->di_dmevmask || from->di_dmstate)
xfs_iflags_set(ip, XFS_IPRESERVE_DM_FIELDS);
if (xfs_sb_version_has_v3inode(&ip->i_mount->m_sb)) {
inode_set_iversion_queried(inode,
be64_to_cpu(from->di_changecount));
ip->i_crtime = xfs_inode_from_disk_ts(from, from->di_crtime);
ip->i_diflags2 = be64_to_cpu(from->di_flags2);
ip->i_cowextsize = be32_to_cpu(from->di_cowextsize);
}
error = xfs_iformat_data_fork(ip, from);
if (error)
return error;
if (from->di_forkoff) {
error = xfs_iformat_attr_fork(ip, from);
if (error)
goto out_destroy_data_fork;
}
if (xfs_is_reflink_inode(ip))
xfs_ifork_init_cow(ip);
return 0;
out_destroy_data_fork:
xfs_idestroy_fork(&ip->i_df);
return error;
}
/* Convert an incore timestamp to an ondisk timestamp. */
static inline xfs_timestamp_t
xfs_inode_to_disk_ts(
struct xfs_inode *ip,
const struct timespec64 tv)
{
struct xfs_legacy_timestamp *lts;
xfs_timestamp_t ts;
if (xfs_inode_has_bigtime(ip))
return cpu_to_be64(xfs_inode_encode_bigtime(tv));
lts = (struct xfs_legacy_timestamp *)&ts;
lts->t_sec = cpu_to_be32(tv.tv_sec);
lts->t_nsec = cpu_to_be32(tv.tv_nsec);
return ts;
}
void
xfs_inode_to_disk(
struct xfs_inode *ip,
struct xfs_dinode *to,
xfs_lsn_t lsn)
{
struct inode *inode = VFS_I(ip);
to->di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
to->di_onlink = 0;
to->di_format = xfs_ifork_format(&ip->i_df);
to->di_uid = cpu_to_be32(i_uid_read(inode));
to->di_gid = cpu_to_be32(i_gid_read(inode));
to->di_projid_lo = cpu_to_be16(ip->i_projid & 0xffff);
to->di_projid_hi = cpu_to_be16(ip->i_projid >> 16);
memset(to->di_pad, 0, sizeof(to->di_pad));
to->di_atime = xfs_inode_to_disk_ts(ip, inode->i_atime);
to->di_mtime = xfs_inode_to_disk_ts(ip, inode->i_mtime);
to->di_ctime = xfs_inode_to_disk_ts(ip, inode->i_ctime);
to->di_nlink = cpu_to_be32(inode->i_nlink);
to->di_gen = cpu_to_be32(inode->i_generation);
to->di_mode = cpu_to_be16(inode->i_mode);
to->di_size = cpu_to_be64(ip->i_disk_size);
to->di_nblocks = cpu_to_be64(ip->i_nblocks);
to->di_extsize = cpu_to_be32(ip->i_extsize);
to->di_nextents = cpu_to_be32(xfs_ifork_nextents(&ip->i_df));
to->di_anextents = cpu_to_be16(xfs_ifork_nextents(ip->i_afp));
to->di_forkoff = ip->i_forkoff;
to->di_aformat = xfs_ifork_format(ip->i_afp);
to->di_flags = cpu_to_be16(ip->i_diflags);
if (xfs_sb_version_has_v3inode(&ip->i_mount->m_sb)) {
to->di_version = 3;
to->di_changecount = cpu_to_be64(inode_peek_iversion(inode));
to->di_crtime = xfs_inode_to_disk_ts(ip, ip->i_crtime);
to->di_flags2 = cpu_to_be64(ip->i_diflags2);
to->di_cowextsize = cpu_to_be32(ip->i_cowextsize);
to->di_ino = cpu_to_be64(ip->i_ino);
to->di_lsn = cpu_to_be64(lsn);
memset(to->di_pad2, 0, sizeof(to->di_pad2));
uuid_copy(&to->di_uuid, &ip->i_mount->m_sb.sb_meta_uuid);
to->di_flushiter = 0;
} else {
to->di_version = 2;
to->di_flushiter = cpu_to_be16(ip->i_flushiter);
}
}
static xfs_failaddr_t
xfs_dinode_verify_fork(
struct xfs_dinode *dip,
struct xfs_mount *mp,
int whichfork)
{
uint32_t di_nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
switch (XFS_DFORK_FORMAT(dip, whichfork)) {
case XFS_DINODE_FMT_LOCAL:
/*
* no local regular files yet
*/
if (whichfork == XFS_DATA_FORK) {
if (S_ISREG(be16_to_cpu(dip->di_mode)))
return __this_address;
if (be64_to_cpu(dip->di_size) >
XFS_DFORK_SIZE(dip, mp, whichfork))
return __this_address;
}
if (di_nextents)
return __this_address;
break;
case XFS_DINODE_FMT_EXTENTS:
if (di_nextents > XFS_DFORK_MAXEXT(dip, mp, whichfork))
return __this_address;
break;
case XFS_DINODE_FMT_BTREE:
if (whichfork == XFS_ATTR_FORK) {
if (di_nextents > MAXAEXTNUM)
return __this_address;
} else if (di_nextents > MAXEXTNUM) {
return __this_address;
}
break;
default:
return __this_address;
}
return NULL;
}
static xfs_failaddr_t
xfs_dinode_verify_forkoff(
struct xfs_dinode *dip,
struct xfs_mount *mp)
{
if (!dip->di_forkoff)
return NULL;
switch (dip->di_format) {
case XFS_DINODE_FMT_DEV:
if (dip->di_forkoff != (roundup(sizeof(xfs_dev_t), 8) >> 3))
return __this_address;
break;
case XFS_DINODE_FMT_LOCAL: /* fall through ... */
case XFS_DINODE_FMT_EXTENTS: /* fall through ... */
case XFS_DINODE_FMT_BTREE:
if (dip->di_forkoff >= (XFS_LITINO(mp) >> 3))
return __this_address;
break;
default:
return __this_address;
}
return NULL;
}
xfs_failaddr_t
xfs_dinode_verify(
struct xfs_mount *mp,
xfs_ino_t ino,
struct xfs_dinode *dip)
{
xfs_failaddr_t fa;
uint16_t mode;
uint16_t flags;
uint64_t flags2;
uint64_t di_size;
if (dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))
return __this_address;
/* Verify v3 integrity information first */
if (dip->di_version >= 3) {
if (!xfs_sb_version_has_v3inode(&mp->m_sb))
return __this_address;
if (!xfs_verify_cksum((char *)dip, mp->m_sb.sb_inodesize,
XFS_DINODE_CRC_OFF))
return __this_address;
if (be64_to_cpu(dip->di_ino) != ino)
return __this_address;
if (!uuid_equal(&dip->di_uuid, &mp->m_sb.sb_meta_uuid))
return __this_address;
}
/* don't allow invalid i_size */
di_size = be64_to_cpu(dip->di_size);
if (di_size & (1ULL << 63))
return __this_address;
mode = be16_to_cpu(dip->di_mode);
if (mode && xfs_mode_to_ftype(mode) == XFS_DIR3_FT_UNKNOWN)
return __this_address;
/* No zero-length symlinks/dirs. */
if ((S_ISLNK(mode) || S_ISDIR(mode)) && di_size == 0)
return __this_address;
/* Fork checks carried over from xfs_iformat_fork */
if (mode &&
be32_to_cpu(dip->di_nextents) + be16_to_cpu(dip->di_anextents) >
be64_to_cpu(dip->di_nblocks))
return __this_address;
if (mode && XFS_DFORK_BOFF(dip) > mp->m_sb.sb_inodesize)
return __this_address;
flags = be16_to_cpu(dip->di_flags);
if (mode && (flags & XFS_DIFLAG_REALTIME) && !mp->m_rtdev_targp)
return __this_address;
/* check for illegal values of forkoff */
fa = xfs_dinode_verify_forkoff(dip, mp);
if (fa)
return fa;
/* Do we have appropriate data fork formats for the mode? */
switch (mode & S_IFMT) {
case S_IFIFO:
case S_IFCHR:
case S_IFBLK:
case S_IFSOCK:
if (dip->di_format != XFS_DINODE_FMT_DEV)
return __this_address;
break;
case S_IFREG:
case S_IFLNK:
case S_IFDIR:
fa = xfs_dinode_verify_fork(dip, mp, XFS_DATA_FORK);
if (fa)
return fa;
break;
case 0:
/* Uninitialized inode ok. */
break;
default:
return __this_address;
}
if (dip->di_forkoff) {
fa = xfs_dinode_verify_fork(dip, mp, XFS_ATTR_FORK);
if (fa)
return fa;
} else {
/*
* If there is no fork offset, this may be a freshly-made inode
* in a new disk cluster, in which case di_aformat is zeroed.
* Otherwise, such an inode must be in EXTENTS format; this goes
* for freed inodes as well.
*/
switch (dip->di_aformat) {
case 0:
case XFS_DINODE_FMT_EXTENTS:
break;
default:
return __this_address;
}
if (dip->di_anextents)
return __this_address;
}
/* extent size hint validation */
fa = xfs_inode_validate_extsize(mp, be32_to_cpu(dip->di_extsize),
mode, flags);
if (fa)
return fa;
/* only version 3 or greater inodes are extensively verified here */
if (dip->di_version < 3)
return NULL;
flags2 = be64_to_cpu(dip->di_flags2);
/* don't allow reflink/cowextsize if we don't have reflink */
if ((flags2 & (XFS_DIFLAG2_REFLINK | XFS_DIFLAG2_COWEXTSIZE)) &&
!xfs_sb_version_hasreflink(&mp->m_sb))
return __this_address;
/* only regular files get reflink */
if ((flags2 & XFS_DIFLAG2_REFLINK) && (mode & S_IFMT) != S_IFREG)
return __this_address;
/* don't let reflink and realtime mix */
if ((flags2 & XFS_DIFLAG2_REFLINK) && (flags & XFS_DIFLAG_REALTIME))
return __this_address;
/* COW extent size hint validation */
fa = xfs_inode_validate_cowextsize(mp, be32_to_cpu(dip->di_cowextsize),
mode, flags, flags2);
if (fa)
return fa;
/* bigtime iflag can only happen on bigtime filesystems */
if (xfs_dinode_has_bigtime(dip) &&
!xfs_sb_version_hasbigtime(&mp->m_sb))
return __this_address;
return NULL;
}
void
xfs_dinode_calc_crc(
struct xfs_mount *mp,
struct xfs_dinode *dip)
{
uint32_t crc;
if (dip->di_version < 3)
return;
ASSERT(xfs_sb_version_hascrc(&mp->m_sb));
crc = xfs_start_cksum_update((char *)dip, mp->m_sb.sb_inodesize,
XFS_DINODE_CRC_OFF);
dip->di_crc = xfs_end_cksum(crc);
}
/*
* Validate di_extsize hint.
*
* 1. Extent size hint is only valid for directories and regular files.
* 2. FS_XFLAG_EXTSIZE is only valid for regular files.
* 3. FS_XFLAG_EXTSZINHERIT is only valid for directories.
* 4. Hint cannot be larger than MAXTEXTLEN.
* 5. Can be changed on directories at any time.
* 6. Hint value of 0 turns off hints, clears inode flags.
* 7. Extent size must be a multiple of the appropriate block size.
* For realtime files, this is the rt extent size.
* 8. For non-realtime files, the extent size hint must be limited
* to half the AG size to avoid alignment extending the extent beyond the
* limits of the AG.
*/
xfs_failaddr_t
xfs_inode_validate_extsize(
struct xfs_mount *mp,
uint32_t extsize,
uint16_t mode,
uint16_t flags)
{
bool rt_flag;
bool hint_flag;
bool inherit_flag;
uint32_t extsize_bytes;
uint32_t blocksize_bytes;
rt_flag = (flags & XFS_DIFLAG_REALTIME);
hint_flag = (flags & XFS_DIFLAG_EXTSIZE);
inherit_flag = (flags & XFS_DIFLAG_EXTSZINHERIT);
extsize_bytes = XFS_FSB_TO_B(mp, extsize);
/*
* This comment describes a historic gap in this verifier function.
*
* On older kernels, the extent size hint verifier doesn't check that
* the extent size hint is an integer multiple of the realtime extent
* size on a directory with both RTINHERIT and EXTSZINHERIT flags set.
* The verifier has always enforced the alignment rule for regular
* files with the REALTIME flag set.
*
* If a directory with a misaligned extent size hint is allowed to
* propagate that hint into a new regular realtime file, the result
* is that the inode cluster buffer verifier will trigger a corruption
* shutdown the next time it is run.
*
* Unfortunately, there could be filesystems with these misconfigured
* directories in the wild, so we cannot add a check to this verifier
* at this time because that will result a new source of directory
* corruption errors when reading an existing filesystem. Instead, we
* permit the misconfiguration to pass through the verifiers so that
* callers of this function can correct and mitigate externally.
*/
if (rt_flag)
blocksize_bytes = mp->m_sb.sb_rextsize << mp->m_sb.sb_blocklog;
else
blocksize_bytes = mp->m_sb.sb_blocksize;
if ((hint_flag || inherit_flag) && !(S_ISDIR(mode) || S_ISREG(mode)))
return __this_address;
if (hint_flag && !S_ISREG(mode))
return __this_address;
if (inherit_flag && !S_ISDIR(mode))
return __this_address;
if ((hint_flag || inherit_flag) && extsize == 0)
return __this_address;
/* free inodes get flags set to zero but extsize remains */
if (mode && !(hint_flag || inherit_flag) && extsize != 0)
return __this_address;
if (extsize_bytes % blocksize_bytes)
return __this_address;
if (extsize > MAXEXTLEN)
return __this_address;
if (!rt_flag && extsize > mp->m_sb.sb_agblocks / 2)
return __this_address;
return NULL;
}
/*
* Validate di_cowextsize hint.
*
* 1. CoW extent size hint can only be set if reflink is enabled on the fs.
* The inode does not have to have any shared blocks, but it must be a v3.
* 2. FS_XFLAG_COWEXTSIZE is only valid for directories and regular files;
* for a directory, the hint is propagated to new files.
* 3. Can be changed on files & directories at any time.
* 4. Hint value of 0 turns off hints, clears inode flags.
* 5. Extent size must be a multiple of the appropriate block size.
* 6. The extent size hint must be limited to half the AG size to avoid
* alignment extending the extent beyond the limits of the AG.
*/
xfs_failaddr_t
xfs_inode_validate_cowextsize(
struct xfs_mount *mp,
uint32_t cowextsize,
uint16_t mode,
uint16_t flags,
uint64_t flags2)
{
bool rt_flag;
bool hint_flag;
uint32_t cowextsize_bytes;
rt_flag = (flags & XFS_DIFLAG_REALTIME);
hint_flag = (flags2 & XFS_DIFLAG2_COWEXTSIZE);
cowextsize_bytes = XFS_FSB_TO_B(mp, cowextsize);
if (hint_flag && !xfs_sb_version_hasreflink(&mp->m_sb))
return __this_address;
if (hint_flag && !(S_ISDIR(mode) || S_ISREG(mode)))
return __this_address;
if (hint_flag && cowextsize == 0)
return __this_address;
/* free inodes get flags set to zero but cowextsize remains */
if (mode && !hint_flag && cowextsize != 0)
return __this_address;
if (hint_flag && rt_flag)
return __this_address;
if (cowextsize_bytes % mp->m_sb.sb_blocksize)
return __this_address;
if (cowextsize > MAXEXTLEN)
return __this_address;
if (cowextsize > mp->m_sb.sb_agblocks / 2)
return __this_address;
return NULL;
}
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