diff --git a/fs/xfs/xfs_zone_alloc.c b/fs/xfs/xfs_zone_alloc.c index 7d13fa7ab30a..bdbb60cc5d5b 100644 --- a/fs/xfs/xfs_zone_alloc.c +++ b/fs/xfs/xfs_zone_alloc.c @@ -793,17 +793,35 @@ xfs_get_cached_zone( rcu_read_lock(); oz = VFS_I(ip)->i_private; - if (oz) { - /* - * GC only steals open zones at mount time, so no GC zones - * should end up in the cache. - */ - ASSERT(!oz->oz_is_gc); - if (!atomic_inc_not_zero(&oz->oz_ref)) - oz = NULL; - } - rcu_read_unlock(); + if (!oz) + goto out_unlock; + /* + * GC only steals open zones at mount time, so no GC zones should end up + * in the cache. + */ + ASSERT(!oz->oz_is_gc); + + /* + * Drop the old cached open zone if it is full. + */ + if (oz->oz_allocated == rtg_blocks(oz->oz_rtg)) { + spin_lock(&ip->i_flags_lock); + oz = VFS_I(ip)->i_private; + if (oz && oz->oz_allocated == rtg_blocks(oz->oz_rtg)) { + VFS_I(ip)->i_private = NULL; + spin_unlock(&ip->i_flags_lock); + xfs_open_zone_put(oz); + oz = NULL; + goto out_unlock; + } + spin_unlock(&ip->i_flags_lock); + } + + if (!atomic_inc_not_zero(&oz->oz_ref)) + oz = NULL; +out_unlock: + rcu_read_unlock(); return oz; } @@ -818,18 +836,41 @@ xfs_get_cached_zone( * that were every written to, but significantly simplifies the cached zone * lookup. Because the open_zone is clearly marked as full when all data * in the underlying RTG was written, the caching is always safe. + * + * Called with a reference on @oz held. And returns two references on the + * returned zone: one for the caller and one for pinning the zone in + * inode->i_private. */ -static void +static struct xfs_open_zone * xfs_set_cached_zone( struct xfs_inode *ip, struct xfs_open_zone *oz) { struct xfs_open_zone *old_oz; + /* + * If the open zone cached in the inode still has free space, use that + * instead of the new open zone just selected. This can happen when + * multiple threads race to perform zone selection for an inode. + * io_uring worker threads seem to be good way to trigger this. + * + * We need to grab an extra reference to this open zone as the caller + * owns a reference in addition to the i_private pointer. + */ + spin_lock(&ip->i_flags_lock); + old_oz = VFS_I(ip)->i_private; + if (old_oz && old_oz->oz_allocated < rtg_blocks(old_oz->oz_rtg) && + atomic_inc_not_zero(&old_oz->oz_ref)) { + spin_unlock(&ip->i_flags_lock); + xfs_open_zone_put(oz); + return old_oz; + } + VFS_I(ip)->i_private = oz; atomic_inc(&oz->oz_ref); - old_oz = xchg(&VFS_I(ip)->i_private, oz); + spin_unlock(&ip->i_flags_lock); if (old_oz) xfs_open_zone_put(old_oz); + return oz; } static void @@ -873,14 +914,13 @@ xfs_zone_alloc_and_submit( * the inode is still associated with a zone and use that if so. */ if (!*oz) - *oz = xfs_get_cached_zone(ip); - - if (!*oz) { select_zone: + *oz = xfs_get_cached_zone(ip); + if (!*oz) { *oz = xfs_select_zone(mp, write_hint, pack_tight); if (!*oz) goto out_error; - xfs_set_cached_zone(ip, *oz); + *oz = xfs_set_cached_zone(ip, *oz); } alloc_len = xfs_zone_alloc_blocks(*oz, XFS_B_TO_FSB(mp, ioend->io_size),