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xfs: support non-power-of-two rtextsize with exchange-range

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The generic exchange-range alignment checks use (fast) bitmasking
operations to perform block alignment checks on the exchange parameters.
Unfortunately, bitmasks require that the alignment size be a power of
two.  This isn't true for realtime devices with a non-power-of-two
extent size, so we have to copy-pasta the generic checks using long
division for this to work properly.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2024-04-15 14:54:23 -07:00
parent e62941103f
commit b3e60f8483
1 changed files with 82 additions and 7 deletions
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89
fs/xfs/xfs_exchrange.c
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@ -504,6 +504,75 @@ xfs_exchange_range_finish(
return file_remove_privs(fxr->file2);
}
/*
* Check the alignment of an exchange request when the allocation unit size
* isn't a power of two. The generic file-level helpers use (fast)
* bitmask-based alignment checks, but here we have to use slow long division.
*/
static int
xfs_exchrange_check_rtalign(
const struct xfs_exchrange *fxr,
struct xfs_inode *ip1,
struct xfs_inode *ip2,
unsigned int alloc_unit)
{
uint64_t length = fxr->length;
uint64_t blen;
loff_t size1, size2;
size1 = i_size_read(VFS_I(ip1));
size2 = i_size_read(VFS_I(ip2));
/* The start of both ranges must be aligned to a rt extent. */
if (!isaligned_64(fxr->file1_offset, alloc_unit) ||
!isaligned_64(fxr->file2_offset, alloc_unit))
return -EINVAL;
if (fxr->flags & XFS_EXCHANGE_RANGE_TO_EOF)
length = max_t(int64_t, size1 - fxr->file1_offset,
size2 - fxr->file2_offset);
/*
* If the user wanted us to exchange up to the infile's EOF, round up
* to the next rt extent boundary for this check. Do the same for the
* outfile.
*
* Otherwise, reject the range length if it's not rt extent aligned.
* We already confirmed the starting offsets' rt extent block
* alignment.
*/
if (fxr->file1_offset + length == size1)
blen = roundup_64(size1, alloc_unit) - fxr->file1_offset;
else if (fxr->file2_offset + length == size2)
blen = roundup_64(size2, alloc_unit) - fxr->file2_offset;
else if (!isaligned_64(length, alloc_unit))
return -EINVAL;
else
blen = length;
/* Don't allow overlapped exchanges within the same file. */
if (ip1 == ip2 &&
fxr->file2_offset + blen > fxr->file1_offset &&
fxr->file1_offset + blen > fxr->file2_offset)
return -EINVAL;
/*
* Ensure that we don't exchange a partial EOF rt extent into the
* middle of another file.
*/
if (isaligned_64(length, alloc_unit))
return 0;
blen = length;
if (fxr->file2_offset + length < size2)
blen = rounddown_64(blen, alloc_unit);
if (fxr->file1_offset + blen < size1)
blen = rounddown_64(blen, alloc_unit);
return blen == length ? 0 : -EINVAL;
}
/* Prepare two files to have their data exchanged. */
STATIC int
xfs_exchrange_prep(
@ -511,6 +580,7 @@ xfs_exchrange_prep(
struct xfs_inode *ip1,
struct xfs_inode *ip2)
{
struct xfs_mount *mp = ip2->i_mount;
unsigned int alloc_unit = xfs_inode_alloc_unitsize(ip2);
int error;
@ -520,13 +590,18 @@ xfs_exchrange_prep(
if (XFS_IS_REALTIME_INODE(ip1) != XFS_IS_REALTIME_INODE(ip2))
return -EINVAL;
/*
* The alignment checks in the generic helpers cannot deal with
* allocation units that are not powers of 2. This can happen with the
* realtime volume if the extent size is set.
*/
if (!is_power_of_2(alloc_unit))
return -EOPNOTSUPP;
/* Check non-power of two alignment issues, if necessary. */
if (!is_power_of_2(alloc_unit)) {
error = xfs_exchrange_check_rtalign(fxr, ip1, ip2, alloc_unit);
if (error)
return error;
/*
* Do the generic file-level checks with the regular block
* alignment.
*/
alloc_unit = mp->m_sb.sb_blocksize;
}
error = xfs_exchange_range_prep(fxr, alloc_unit);
if (error || fxr->length == 0)