diff options
author | Darrick J. Wong <djwong@kernel.org> | 2021-08-10 17:00:31 -0700 |
---|---|---|
committer | Darrick J. Wong <djwong@kernel.org> | 2021-08-18 18:46:00 -0700 |
commit | 9ab72f22277487d2a3ffc8dd20fc918e186bb2b3 (patch) | |
tree | 47b56231c0a590417d851c0d5bf8964ec57b0aa9 | |
parent | c02f6529864a4f5f91d216d324bac4ba75415d19 (diff) |
xfs: fix off-by-one error when the last rt extent is in use
The fsmap implementation for realtime devices uses the gap between
info->next_daddr and a free rtextent reported by xfs_rtalloc_query_range
to feed userspace fsmap records with an "unknown" owner. We use this
trick to report to userspace when the last rtextent in the filesystem is
in use by synthesizing a null rmap record starting at the next block
after the query range.
Unfortunately, there's a minor accounting bug in the way that we
construct the null rmap record. Originally, ahigh.ar_startext contains
the last rtextent for which the user wants records. It's entirely
possible that number is beyond the end of the rt volume, so the location
synthesized rmap record /must/ be constrained to the minimum of the high
key and the number of extents in the rt volume.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
-rw-r--r-- | fs/xfs/xfs_fsmap.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index 7d0b09c1366e..5f603ed3f678 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -523,27 +523,37 @@ xfs_getfsmap_rtdev_rtbitmap_query( { struct xfs_rtalloc_rec alow = { 0 }; struct xfs_rtalloc_rec ahigh = { 0 }; + struct xfs_mount *mp = tp->t_mountp; int error; - xfs_ilock(tp->t_mountp->m_rbmip, XFS_ILOCK_SHARED); + xfs_ilock(mp->m_rbmip, XFS_ILOCK_SHARED); + /* + * Set up query parameters to return free rtextents covering the range + * we want. + */ alow.ar_startext = info->low.rm_startblock; ahigh.ar_startext = info->high.rm_startblock; - do_div(alow.ar_startext, tp->t_mountp->m_sb.sb_rextsize); - if (do_div(ahigh.ar_startext, tp->t_mountp->m_sb.sb_rextsize)) + do_div(alow.ar_startext, mp->m_sb.sb_rextsize); + if (do_div(ahigh.ar_startext, mp->m_sb.sb_rextsize)) ahigh.ar_startext++; error = xfs_rtalloc_query_range(tp, &alow, &ahigh, xfs_getfsmap_rtdev_rtbitmap_helper, info); if (error) goto err; - /* Report any gaps at the end of the rtbitmap */ + /* + * Report any gaps at the end of the rtbitmap by simulating a null + * rmap starting at the block after the end of the query range. + */ info->last = true; + ahigh.ar_startext = min(mp->m_sb.sb_rextents, ahigh.ar_startext); + error = xfs_getfsmap_rtdev_rtbitmap_helper(tp, &ahigh, info); if (error) goto err; err: - xfs_iunlock(tp->t_mountp->m_rbmip, XFS_ILOCK_SHARED); + xfs_iunlock(mp->m_rbmip, XFS_ILOCK_SHARED); return error; } |