[PATCH 35/38] xfs_repair: fix maximum file offset comparison

Darrick J. Wong
2024-10-11T01:23:16Z

When running generic/525 with rtinherit=1 and rextsize=28k, generic/525
trips over the following block mapping:

data offset 2251799813685247 startblock 7 (0/7) count 1 flag 0
data offset 2251799813685248 startblock 8 (0/8) count 6 flag 1

with this error:

inode 155 - extent exceeds max offset - start 2251799813685248, count 6,
physical block 8

This is due to an incorrect check in xfs_repair, which tries to validate
that a block mapping cannot exceed what it thinks is the maximum file
offset. Unfortunately, the check is wrong, because only br_startoff is
subject to the 2^52-1 limit -- not br_startoff + br_blockcount.

Nowadays libxfs provides a symbol XFS_MAX_FILEOFF for the maximum
allowable file block offset that can be mapped into a file. Use this
instead of the open-coded logic in versions.c and correct all the other
checks. Note that this problem only surfaced when rtgroups were enabled
because hch changed xfs_repair to use the same tree-based block state
data structure that we use for AGs when rtgroups are enabled.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
repair/dinode.c | 2 +-
repair/globals.c | 1 -
repair/globals.h | 1 -
repair/prefetch.c | 2 +-
repair/versions.c | 7 +------
5 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/repair/dinode.c b/repair/dinode.c
index fb234e259afd83..1d2d4ffa6d0e53 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -501,7 +501,7 @@ _("inode %" PRIu64 " - bad extent overflows - start %" PRIu64 ", "
}
/* Ensure this extent does not extend beyond the max offset */
if (irec.br_startoff + irec.br_blockcount - 1 >
- fs_max_file_offset) {
+ XFS_MAX_FILEOFF) {
do_warn(
_("inode %" PRIu64 " - extent exceeds max offset - start %" PRIu64 ", "
"count %" PRIu64 ", physical block %" PRIu64 "\n"),
diff --git a/repair/globals.c b/repair/globals.c
index 07f7526a73a0b1..b63931be9fdb70 100644
--- a/repair/globals.c
+++ b/repair/globals.c
@@ -86,7 +86,6 @@ int inodes_per_block;
unsigned int glob_agcount;
int chunks_pblock; /* # of 64-ino chunks per allocation */
int max_symlink_blocks;
-int64_t fs_max_file_offset;

/* realtime info */

diff --git a/repair/globals.h b/repair/globals.h
index 7db710a266b3c7..1dc85ce7f8114c 100644
--- a/repair/globals.h
+++ b/repair/globals.h
@@ -127,7 +127,6 @@ extern int inodes_per_block;
extern unsigned int glob_agcount;
extern int chunks_pblock; /* # of 64-ino chunks per allocation */
extern int max_symlink_blocks;
-extern int64_t fs_max_file_offset;

/* realtime info */

diff --git a/repair/prefetch.c b/repair/prefetch.c
index 998797e3696bac..27ef15708aa0ea 100644
--- a/repair/prefetch.c
+++ b/repair/prefetch.c
@@ -185,7 +185,7 @@ pf_read_bmbt_reclist(

if (((i > 0) && (op + cp > irec.br_startoff)) ||
(irec.br_blockcount == 0) ||
- (irec.br_startoff >= fs_max_file_offset))
+ (irec.br_startoff + irec.br_blockcount - 1 >= XFS_MAX_FILEOFF))
goto out_free;

if (!libxfs_verify_fsbno(mp, irec.br_startblock) ||
diff --git a/repair/versions.c b/repair/versions.c
index b24965b263a183..7dc91b4597eece 100644
--- a/repair/versions.c
+++ b/repair/versions.c
@@ -180,10 +180,5 @@ _("WARNING: you have a V1 inode filesystem. It would be converted to a\n"
fs_ino_alignment = mp->m_sb.sb_inoalignmt;
}

- /*
- * calculate maximum file offset for this geometry
- */
- fs_max_file_offset = 0x7fffffffffffffffLL >> mp->m_sb.sb_blocklog;
-
- return(0);
+ return 0;
}