On Mon, Jan 06, 2025 at 11:52:20AM -0800, Darrick J. Wong wrote: > On Tue, Dec 31, 2024 at 10:34:22AM +0800, Long Li wrote: > > When mounting an xfs disk that incompat with metadir and has no realtime > > subvolume, if CONFIG_XFS_RT is not enabled in the kernel, the mount will > > fail. During superblock log recovery, since mp->m_sb.sb_rgcount is greater > > than 0, updating the last rtag in-core is required, however, without > > CONFIG_XFS_RT enabled, xfs_update_last_rtgroup_size() always returns > > -EOPNOTSUPP, leading to mount failure. > > Didn't we fix the xfs_update_last_rtgroup_size stub to return 0? > > --D Indeed, when CONFIG_XFS_RT is not enabled, xfs_update_last_rtgroup_size() should return 0, as returning an error is meaningless. 1) For kernels without CONFIG_XFS_RT, mounting an image with realtime subvolume will fail at xfs_rtmount_init(). 2) For kernels without CONFIG_XFS_RT, mounting an image without realtime subvolume should succeed. However, in the current scenario, should sb_rgcount be initialized to 0 ? it will consistent with metadir feature is enabled. The xfs-documentation [1] describes sb_rgcount as follows: "Count of realtime groups in the filesystem, if the XFS_SB_FEAT_RO_INCOMPAT_METADIR feature is enabled. If no realtime subvolume exists, this value will be zero." [1] https://git.kernel.org/pub/scm/fs/xfs/xfs-documentation.git/tree/design/XFS_Filesystem_Structure/superblock.asciidoc Thanks, Long Li > > > Initializing sb_rgcount as 1 is incorrect in this scenario. If no > > realtime subvolume exists, the value of sb_rgcount should be set > > to zero. Fix it by initializing sb_rgcount based on the actual number > > of realtime blocks. > > > > Fixes: 87fe4c34a383 ("xfs: create incore realtime group structures") > > Signed-off-by: Long Li <leo.lilong@xxxxxxxxxx> > > --- > > fs/xfs/libxfs/xfs_sb.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c > > index 3b5623611eba..1ea28f04b75a 100644 > > --- a/fs/xfs/libxfs/xfs_sb.c > > +++ b/fs/xfs/libxfs/xfs_sb.c > > @@ -830,7 +830,7 @@ __xfs_sb_from_disk( > > to->sb_rsumino = NULLFSINO; > > } else { > > to->sb_metadirino = NULLFSINO; > > - to->sb_rgcount = 1; > > + to->sb_rgcount = to->sb_rblocks > 0 ? 1 : 0; > > to->sb_rgextents = 0; > > } > > } > > -- > > 2.39.2 > > > > >
