From 9e13975bb0620c2bfa1a4d2943e7eb8514f7708e Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Sun, 6 Nov 2022 17:03:18 -0800 Subject: [PATCH 1/2] xfs: load rtbitmap and rtsummary extent mapping btrees at mount time It turns out that GETFSMAP and online fsck have had a bug for years due to their use of ILOCK_SHARED to coordinate their linear scans of the realtime bitmap. If the bitmap file's data fork happens to be in BTREE format and the scan occurs immediately after mounting, the incore bmbt will not be populated, leading to ASSERTs tripping over the incorrect inode state. Because the bitmap scans always lock bitmap buffers in increasing order of file offset, it is appropriate for these two callers to take a shared ILOCK to improve scalability. To fix this problem, load both data and attr fork state into memory when mounting the realtime inodes. Realtime metadata files aren't supposed to have an attr fork so the second step is likely a nop. On most filesystems this is unlikely since the rtbitmap data fork is usually in extents format, but it's possible to craft a filesystem that will by fragmenting the free space in the data section and growfsing the rt section. Fixes: 4c934c7dd60c ("xfs: report realtime space information via the rtbitmap") Also-Fixes: 46d9bfb5e706 ("xfs: cross-reference the realtime bitmap") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner --- fs/xfs/xfs_rtalloc.c | 56 ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 52 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c index 292d5e54a92c..b0846204c436 100644 --- a/fs/xfs/xfs_rtalloc.c +++ b/fs/xfs/xfs_rtalloc.c @@ -1325,6 +1325,41 @@ xfs_rtalloc_reinit_frextents( return 0; } +/* + * Read in the bmbt of an rt metadata inode so that we never have to load them + * at runtime. This enables the use of shared ILOCKs for rtbitmap scans. Use + * an empty transaction to avoid deadlocking on loops in the bmbt. + */ +static inline int +xfs_rtmount_iread_extents( + struct xfs_inode *ip, + unsigned int lock_class) +{ + struct xfs_trans *tp; + int error; + + error = xfs_trans_alloc_empty(ip->i_mount, &tp); + if (error) + return error; + + xfs_ilock(ip, XFS_ILOCK_EXCL | lock_class); + + error = xfs_iread_extents(tp, ip, XFS_DATA_FORK); + if (error) + goto out_unlock; + + if (xfs_inode_has_attr_fork(ip)) { + error = xfs_iread_extents(tp, ip, XFS_ATTR_FORK); + if (error) + goto out_unlock; + } + +out_unlock: + xfs_iunlock(ip, XFS_ILOCK_EXCL | lock_class); + xfs_trans_cancel(tp); + return error; +} + /* * Get the bitmap and summary inodes and the summary cache into the mount * structure at mount time. @@ -1342,14 +1377,27 @@ xfs_rtmount_inodes( return error; ASSERT(mp->m_rbmip != NULL); + error = xfs_rtmount_iread_extents(mp->m_rbmip, XFS_ILOCK_RTBITMAP); + if (error) + goto out_rele_bitmap; + error = xfs_iget(mp, NULL, sbp->sb_rsumino, 0, 0, &mp->m_rsumip); - if (error) { - xfs_irele(mp->m_rbmip); - return error; - } + if (error) + goto out_rele_bitmap; ASSERT(mp->m_rsumip != NULL); + + error = xfs_rtmount_iread_extents(mp->m_rsumip, XFS_ILOCK_RTSUM); + if (error) + goto out_rele_summary; + xfs_alloc_rsum_cache(mp, sbp->sb_rbmblocks); return 0; + +out_rele_summary: + xfs_irele(mp->m_rsumip); +out_rele_bitmap: + xfs_irele(mp->m_rbmip); + return error; } void From 5f369dc5b4eb2becbdfd08924dcaf00e391f4ea1 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Sun, 6 Nov 2022 17:03:18 -0800 Subject: [PATCH 2/2] xfs: make rtbitmap ILOCKing consistent when scanning the rt bitmap file xfs_rtalloc_query_range scans the realtime bitmap file in order of increasing file offset, so this caller can take ILOCK_SHARED on the rt bitmap inode instead of ILOCK_EXCL. This isn't going to yield any practical benefits at mount time, but we'd like to make the locking usage consistent around xfs_rtalloc_query_all calls. Make all the places we do this use the same xfs_ilock lockflags for consistency. Fixes: 4c934c7dd60c ("xfs: report realtime space information via the rtbitmap") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner --- fs/xfs/xfs_fsmap.c | 4 ++-- fs/xfs/xfs_rtalloc.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index d8337274c74d..88a88506ffff 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -524,7 +524,7 @@ xfs_getfsmap_rtdev_rtbitmap_query( struct xfs_mount *mp = tp->t_mountp; int error; - xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED); + xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP); /* * Set up query parameters to return free rtextents covering the range @@ -551,7 +551,7 @@ xfs_getfsmap_rtdev_rtbitmap_query( if (error) goto err; err: - xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED); + xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP); return error; } diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c index b0846204c436..16534e9873f6 100644 --- a/fs/xfs/xfs_rtalloc.c +++ b/fs/xfs/xfs_rtalloc.c @@ -1311,10 +1311,10 @@ xfs_rtalloc_reinit_frextents( uint64_t val = 0; int error; - xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL); + xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP); error = xfs_rtalloc_query_all(mp, NULL, xfs_rtalloc_count_frextent, &val); - xfs_iunlock(mp->m_rbmip, XFS_ILOCK_EXCL); + xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP); if (error) return error;