From b3e60f84838d5abc3a73d7ef0fc595dd1041c565 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 15 Apr 2024 14:54:23 -0700 Subject: [PATCH] xfs: support non-power-of-two rtextsize with exchange-range 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 Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_exchrange.c | 89 ++++++++++++++++++++++++++++++++++++++---- 1 file changed, 82 insertions(+), 7 deletions(-) diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c index 90baf12bd97f..c8a655c92c92 100644 --- a/fs/xfs/xfs_exchrange.c +++ b/fs/xfs/xfs_exchrange.c @@ -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) -- 2.25.1