mainline inclusion from mainline-v6.11-rc6 commit ca6448aed4f10ad88eba79055f181eb9a589a7b3 category: bugfix bugzilla: 190381
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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In the fsmap query of xfs, there is an interval missing problem: [root@fedora ~]# xfs_io -c 'fsmap -vvvv' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:16 [0..7]: static fs metadata 0 (0..7) 8 1: 253:16 [8..23]: per-AG metadata 0 (8..23) 16 2: 253:16 [24..39]: inode btree 0 (24..39) 16 3: 253:16 [40..47]: per-AG metadata 0 (40..47) 8 4: 253:16 [48..55]: refcount btree 0 (48..55) 8 5: 253:16 [56..103]: per-AG metadata 0 (56..103) 48 6: 253:16 [104..127]: free space 0 (104..127) 24 ......
BUG: [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 104 107' /mnt [root@fedora ~]# Normally, we should be able to get [104, 107), but we got nothing.
The problem is caused by shifting. The query for the problem-triggered scenario is for the missing_owner interval (e.g. freespace in rmapbt/ unknown space in bnobt), which is obtained by subtraction (gap). For this scenario, the interval is obtained by info->last. However, rec_daddr is calculated based on the start_block recorded in key[1], which is converted by calling XFS_BB_TO_FSBT. Then if rec_daddr does not exceed info->next_daddr, which means keys[1].fmr_physical >> (mp)->m_blkbb_log <= info->next_daddr, no records will be displayed. In the above example, 104 >> (mp)->m_blkbb_log = 12 and 107 >> (mp)->m_blkbb_log = 12, so the two are reduced to 0 and the gap is ignored:
before calculate ----------------> after shifting 104(st) 107(ed) 12(st/ed) |---------| | sector size block size
Resolve this issue by introducing the "end_daddr" field in xfs_getfsmap_info. This records |key[1].fmr_physical + key[1].length| at the granularity of sector. If the current query is the last, the rec_daddr is end_daddr to prevent missing interval problems caused by shifting. We only need to focus on the last query, because xfs disks are internally aligned with disk blocksize that are powers of two and minimum 512, so there is no problem with shifting in previous queries.
After applying this patch, the above problem have been solved: [root@fedora ~]# xfs_io -c 'fsmap -vvvv -d 104 107' /mnt EXT: DEV BLOCK-RANGE OWNER FILE-OFFSET AG AG-OFFSET TOTAL 0: 253:16 [104..106]: free space 0 (104..106) 3
Fixes: e89c041338ed ("xfs: implement the GETFSMAP ioctl") Signed-off-by: Zizhi Wo wozizhi@huawei.com Reviewed-by: Darrick J. Wong djwong@kernel.org [djwong: limit the range of end_addr correctly] Signed-off-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Chandan Babu R chandanbabu@kernel.org
Conflicts: fs/xfs/xfs_fsmap.c [Simple context conflicts in the xfs_getfsmap_info structure.]
Signed-off-by: Zizhi Wo wozizhi@huawei.com --- fs/xfs/xfs_fsmap.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index 595450a99ae2..001dbc68cf90 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -158,6 +158,7 @@ struct xfs_getfsmap_info { struct fsmap *fsmap_recs; /* mapping records */ struct xfs_buf *agf_bp; /* AGF, for refcount queries */ xfs_daddr_t next_daddr; /* next daddr we expect */ + xfs_daddr_t end_daddr; /* daddr of high fsmap key */ u64 missing_owner; /* owner of holes */ u32 dev; /* device id */ xfs_agnumber_t agno; /* AG number, if applicable */ @@ -172,6 +173,7 @@ struct xfs_getfsmap_dev { int (*fn)(struct xfs_trans *tp, const struct xfs_fsmap *keys, struct xfs_getfsmap_info *info); + sector_t nr_sectors; };
/* Compare two getfsmap device handlers. */ @@ -267,6 +269,18 @@ xfs_getfsmap_helper( return 0; }
+ /* + * For an info->last query, we're looking for a gap between the last + * mapping emitted and the high key specified by userspace. If the + * user's query spans less than 1 fsblock, then info->high and + * info->low will have the same rm_startblock, which causes rec_daddr + * and next_daddr to be the same. Therefore, use the end_daddr that + * we calculated from userspace's high key to synthesize the record. + * Note that if the btree query found a mapping, there won't be a gap. + */ + if (info->last && info->end_daddr != XFS_BUF_DADDR_NULL) + rec_daddr = info->end_daddr; + /* Are we just counting mappings? */ if (info->head->fmh_count == 0) { if (info->head->fmh_entries == UINT_MAX) @@ -855,17 +869,21 @@ xfs_getfsmap(
/* Set up our device handlers. */ memset(handlers, 0, sizeof(handlers)); + handlers[0].nr_sectors = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks); handlers[0].dev = new_encode_dev(mp->m_ddev_targp->bt_dev); if (use_rmap) handlers[0].fn = xfs_getfsmap_datadev_rmapbt; else handlers[0].fn = xfs_getfsmap_datadev_bnobt; if (mp->m_logdev_targp != mp->m_ddev_targp) { + handlers[1].nr_sectors = XFS_FSB_TO_BB(mp, + mp->m_sb.sb_logblocks); handlers[1].dev = new_encode_dev(mp->m_logdev_targp->bt_dev); handlers[1].fn = xfs_getfsmap_logdev; } #ifdef CONFIG_XFS_RT if (mp->m_rtdev_targp) { + handlers[2].nr_sectors = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks); handlers[2].dev = new_encode_dev(mp->m_rtdev_targp->bt_dev); handlers[2].fn = xfs_getfsmap_rtdev_rtbitmap; } @@ -908,6 +926,7 @@ xfs_getfsmap(
info.next_daddr = head->fmh_keys[0].fmr_physical + head->fmh_keys[0].fmr_length; + info.end_daddr = XFS_BUF_DADDR_NULL; info.fsmap_recs = fsmap_recs; info.head = head;
@@ -936,8 +955,11 @@ xfs_getfsmap( * low key, zero out the low key so that we get * everything from the beginning. */ - if (handlers[i].dev == head->fmh_keys[1].fmr_device) + if (handlers[i].dev == head->fmh_keys[1].fmr_device) { dkeys[1] = head->fmh_keys[1]; + info.end_daddr = min(handlers[i].nr_sectors - 1, + dkeys[1].fmr_physical); + } if (handlers[i].dev > head->fmh_keys[0].fmr_device) memset(&dkeys[0], 0, sizeof(struct xfs_fsmap));