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xfs: assert the reservation covers each da fork growth

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xfs_da_grow_inode_int() subtracts the blocks it just allocated from
args->total, the caller's remaining block reservation.  The subtraction
is unsigned, so a caller that reaches it with too small a total wraps
the field instead of failing, and every allocation afterwards runs with
a bogus reservation.  Assert the remaining reservation still covers the
step, so an under-reserved or uninitialised total trips in debug builds
instead of silently wrapping.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Javier Tia <floss@jetm.me>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Javier Tia 2026-08-10 17:06:18 -06:00 committed by Carlos Maiolino
parent 8e4ebb6afa
commit 0fe77e5758
1 changed files with 1 additions and 0 deletions
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fs/xfs/libxfs/xfs_da_btree.c
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@ -2384,6 +2384,7 @@ xfs_da_grow_inode_int(
} }
/* account for newly allocated blocks in reserved blocks total */ /* account for newly allocated blocks in reserved blocks total */
ASSERT(args->total >= dp->i_nblocks - nblks);
args->total -= dp->i_nblocks - nblks; args->total -= dp->i_nblocks - nblks;
out_free_map: out_free_map: