diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_alloc.c')
| -rw-r--r-- | fs/xfs/libxfs/xfs_alloc.c | 59 |
1 files changed, 42 insertions, 17 deletions
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index 61eb65be17f3..fd3293a8c659 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -628,6 +628,25 @@ xfs_alloc_fixup_trees( return 0; } +/* + * We do not verify the AGFL contents against AGF-based index counters here, + * even though we may have access to the perag that contains shadow copies. We + * don't know if the AGF based counters have been checked, and if they have they + * still may be inconsistent because they haven't yet been reset on the first + * allocation after the AGF has been read in. + * + * This means we can only check that all agfl entries contain valid or null + * values because we can't reliably determine the active range to exclude + * NULLAGBNO as a valid value. + * + * However, we can't even do that for v4 format filesystems because there are + * old versions of mkfs out there that does not initialise the AGFL to known, + * verifiable values. HEnce we can't tell the difference between a AGFL block + * allocated by mkfs and a corrupted AGFL block here on v4 filesystems. + * + * As a result, we can only fully validate AGFL block numbers when we pull them + * from the freelist in xfs_alloc_get_freelist(). + */ static xfs_failaddr_t xfs_agfl_verify( struct xfs_buf *bp) @@ -637,12 +656,6 @@ xfs_agfl_verify( __be32 *agfl_bno = xfs_buf_to_agfl_bno(bp); int i; - /* - * There is no verification of non-crc AGFLs because mkfs does not - * initialise the AGFL to zero or NULL. Hence the only valid part of the - * AGFL is what the AGF says is active. We can't get to the AGF, so we - * can't verify just those entries are valid. - */ if (!xfs_has_crc(mp)) return NULL; @@ -2321,12 +2334,16 @@ xfs_free_agfl_block( } /* - * Check the agfl fields of the agf for inconsistency or corruption. The purpose - * is to detect an agfl header padding mismatch between current and early v5 - * kernels. This problem manifests as a 1-slot size difference between the - * on-disk flcount and the active [first, last] range of a wrapped agfl. This - * may also catch variants of agfl count corruption unrelated to padding. Either - * way, we'll reset the agfl and warn the user. + * Check the agfl fields of the agf for inconsistency or corruption. + * + * The original purpose was to detect an agfl header padding mismatch between + * current and early v5 kernels. This problem manifests as a 1-slot size + * difference between the on-disk flcount and the active [first, last] range of + * a wrapped agfl. + * + * However, we need to use these same checks to catch agfl count corruptions + * unrelated to padding. This could occur on any v4 or v5 filesystem, so either + * way, we need to reset the agfl and warn the user. * * Return true if a reset is required before the agfl can be used, false * otherwise. @@ -2342,10 +2359,6 @@ xfs_agfl_needs_reset( int agfl_size = xfs_agfl_size(mp); int active; - /* no agfl header on v4 supers */ - if (!xfs_has_crc(mp)) - return false; - /* * The agf read verifier catches severe corruption of these fields. * Repeat some sanity checks to cover a packed -> unpacked mismatch if @@ -2889,6 +2902,19 @@ xfs_alloc_put_freelist( return 0; } +/* + * Verify the AGF is consistent. + * + * We do not verify the AGFL indexes in the AGF are fully consistent here + * because of issues with variable on-disk structure sizes. Instead, we check + * the agfl indexes for consistency when we initialise the perag from the AGF + * information after a read completes. + * + * If the index is inconsistent, then we mark the perag as needing an AGFL + * reset. The first AGFL update performed then resets the AGFL indexes and + * refills the AGFL with known good free blocks, allowing the filesystem to + * continue operating normally at the cost of a few leaked free space blocks. + */ static xfs_failaddr_t xfs_agf_verify( struct xfs_buf *bp) @@ -2962,7 +2988,6 @@ xfs_agf_verify( return __this_address; return NULL; - } static void |