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xfs: fix the rtrmap and rtrefcount _maxlevels_ondisk functions

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The _maxlevels_ondisk functions are used to compute the size of
in-memory btree cursors for each btree type.  Unfortunately, LOLLM
noticed that the rtrmap and rtrefcount versions of these functions
forget to account for the inode root, which means that we could access
beyond the end of the cursor given a sufficiently large btree.  Fix
this.

Cc: stable@vger.kernel.org # v6.14
Fixes: 9abe03a0e4 ("xfs: introduce realtime refcount btree ondisk definitions")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Darrick J. Wong 2026-09-01 22:43:02 -07:00 committed by Carlos Maiolino
parent 2eac8d01d2
commit aa301322f7
2 changed files with 8 additions and 3 deletions
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7
fs/xfs/libxfs/xfs_rtrefcount_btree.c
View File

@ -489,8 +489,11 @@ xfs_rtrefcountbt_maxlevels_ondisk(void)
minrecs[0] = xfs_rtrefcountbt_block_maxrecs(blocklen, true) / 2;
minrecs[1] = xfs_rtrefcountbt_block_maxrecs(blocklen, false) / 2;
/* We need at most one record for every block in an rt group. */
return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_RGBLOCKS);
/*
* We need at most one record for every block in an rt group, and
* one extra level for the inode root.
*/
return xfs_btree_compute_maxlevels(minrecs, XFS_MAX_RGBLOCKS) + 1;
}
int __init

4
fs/xfs/libxfs/xfs_rtrmap_btree.c
View File

@ -716,10 +716,12 @@ xfs_rtrmapbt_maxlevels_ondisk(void)
* happens, which means that we must compute the max height based on
* what the btree will look like if it consumes almost all the blocks
* in the data device due to maximal sharing factor.
*
* Add one extra level for the inode root.
*/
max_dblocks = -1U; /* max ag count */
max_dblocks *= XFS_MAX_CRC_AG_BLOCKS;
return xfs_btree_space_to_height(minrecs, max_dblocks);
return xfs_btree_space_to_height(minrecs, max_dblocks) + 1;
}
int __init