On Thu, Mar 17, 2022 at 02:21:06PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > The comment for xfs_alloc_set_aside indicates that we want to set aside > enough space to handle a bmap btree split. The code, unfortunately, > hardcodes this to 4. > > This is incorrect, since file bmap btrees can be taller than that: > > xfs_db> btheight bmapbt -n 4294967296 -b 512 > bmapbt: worst case per 512-byte block: 13 records (leaf) / 13 keyptrs (node) > level 0: 4294967296 records, 330382100 blocks > level 1: 330382100 records, 25414008 blocks > level 2: 25414008 records, 1954924 blocks > level 3: 1954924 records, 150379 blocks > level 4: 150379 records, 11568 blocks > level 5: 11568 records, 890 blocks > level 6: 890 records, 69 blocks > level 7: 69 records, 6 blocks > level 8: 6 records, 1 block > 9 levels, 357913945 blocks total > > Fix this by using the actual bmap btree maxlevel value for the > set-aside. We subtract one because the root is always in the inode and > hence never splits. > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > --- > fs/xfs/libxfs/xfs_alloc.c | 7 +++++-- > fs/xfs/libxfs/xfs_sb.c | 2 -- > fs/xfs/xfs_mount.c | 7 +++++++ > 3 files changed, 12 insertions(+), 4 deletions(-) > > ... > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c > index bed73e8002a5..9336176dc706 100644 > --- a/fs/xfs/xfs_mount.c > +++ b/fs/xfs/xfs_mount.c > @@ -652,6 +652,13 @@ xfs_mountfs( > > xfs_agbtree_compute_maxlevels(mp); > > + /* > + * Compute the amount of space to set aside to handle btree splits now > + * that we have calculated the btree maxlevels. > + */ "... to handle btree splits near -ENOSPC ..." ? Otherwise LGTM: Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> > + mp->m_alloc_set_aside = xfs_alloc_set_aside(mp); > + mp->m_ag_max_usable = xfs_alloc_ag_max_usable(mp); > + > /* > * Check if sb_agblocks is aligned at stripe boundary. If sb_agblocks > * is NOT aligned turn off m_dalign since allocator alignment is within >
