6.1-stable review patch. If anyone has any objections, please let me know.
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From: Darrick J. Wong djwong@kernel.org
[ Upstream commit cfa2df68b7ceb49ac9eb2d295ab0c5974dbf17e7 ]
Dave Chinner reported that xfs/273 fails if the AG size happens to be an exact power of two. I traced this to an agbno integer overflow when the current GETFSMAP call is a continuation of a previous GETFSMAP call, and the last record returned was non-shareable space at the end of an AG.
__xfs_getfsmap_datadev sets up a data device query by converting the incoming fmr_physical into an xfs_fsblock_t and cracking it into an agno and agbno pair. In the (failing) case of where fmr_blockcount of the low key is nonzero and the record was for a non-shareable extent, it will add fmr_blockcount to start_fsb and info->low.rm_startblock.
If the low key was actually the last record for that AG, then this addition causes info->low.rm_startblock to point beyond EOAG. When the rmapbt range query starts, it'll return an empty set, and fsmap moves on to the next AG.
Or so I thought. Remember how we added to start_fsb?
If agsize < 1<<agblklog, start_fsb points to the same AG as the original fmr_physical from the low key. We run the rmapbt query, which returns nothing, so getfsmap zeroes info->low and moves on to the next AG.
If agsize == 1<<agblklog, start_fsb now points to the next AG. We run the rmapbt query on the next AG with the excessively large rm_startblock. If this next AG is actually the last AG, we'll set info->high to EOFS (which is now has a lower rm_startblock than info->low), and the ranged btree query code will return -EINVAL. If it's not the last AG, we ignore all records for the intermediate AGs.
Oops.
Fix this by decoding start_fsb into agno and agbno only after making adjustments to start_fsb. This means that info->low.rm_startblock will always be set to a valid agbno, and we always start the rmapbt iteration in the correct AG.
While we're at it, fix the predicate for determining if an fsmap record represents non-shareable space to include file data on pre-reflink filesystems.
Reported-by: Dave Chinner david@fromorbit.com Fixes: 63ef7a35912dd ("xfs: fix interval filtering in multi-step fsmap queries") Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Dave Chinner dchinner@redhat.com Signed-off-by: Leah Rumancik leah.rumancik@gmail.com Acked-by: "Darrick J. Wong" djwong@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/xfs/xfs_fsmap.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index d10f2c719220d..956a5670e56ce 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -565,6 +565,19 @@ xfs_getfsmap_rtdev_rtbitmap( } #endif /* CONFIG_XFS_RT */
+static inline bool +rmap_not_shareable(struct xfs_mount *mp, const struct xfs_rmap_irec *r) +{ + if (!xfs_has_reflink(mp)) + return true; + if (XFS_RMAP_NON_INODE_OWNER(r->rm_owner)) + return true; + if (r->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK | + XFS_RMAP_UNWRITTEN)) + return true; + return false; +} + /* Execute a getfsmap query against the regular data device. */ STATIC int __xfs_getfsmap_datadev( @@ -598,7 +611,6 @@ __xfs_getfsmap_datadev( * low to the fsmap low key and max out the high key to the end * of the AG. */ - info->low.rm_startblock = XFS_FSB_TO_AGBNO(mp, start_fsb); info->low.rm_offset = XFS_BB_TO_FSBT(mp, keys[0].fmr_offset); error = xfs_fsmap_owner_to_rmap(&info->low, &keys[0]); if (error) @@ -608,12 +620,9 @@ __xfs_getfsmap_datadev(
/* Adjust the low key if we are continuing from where we left off. */ if (info->low.rm_blockcount == 0) { - /* empty */ - } else if (XFS_RMAP_NON_INODE_OWNER(info->low.rm_owner) || - (info->low.rm_flags & (XFS_RMAP_ATTR_FORK | - XFS_RMAP_BMBT_BLOCK | - XFS_RMAP_UNWRITTEN))) { - info->low.rm_startblock += info->low.rm_blockcount; + /* No previous record from which to continue */ + } else if (rmap_not_shareable(mp, &info->low)) { + /* Last record seen was an unshareable extent */ info->low.rm_owner = 0; info->low.rm_offset = 0;
@@ -621,8 +630,10 @@ __xfs_getfsmap_datadev( if (XFS_FSB_TO_DADDR(mp, start_fsb) >= eofs) return 0; } else { + /* Last record seen was a shareable file data extent */ info->low.rm_offset += info->low.rm_blockcount; } + info->low.rm_startblock = XFS_FSB_TO_AGBNO(mp, start_fsb);
info->high.rm_startblock = -1U; info->high.rm_owner = ULLONG_MAX;