xfs: read only mounts with fsopen mount API are busted
commit d8d222e0 upstream. Recently xfs/513 started failing on my test machines testing "-o ro,norecovery" mount options. This was being emitted in dmesg: [ 9906.932724] XFS (pmem0): no-recovery mounts must be read-only. Turns out, readonly mounts with the fsopen()/fsconfig() mount API have been busted since day zero. It's only taken 5 years for debian unstable to start using this "new" mount API, and shortly after this I noticed xfs/513 had started to fail as per above. The syscall trace is: fsopen("xfs", FSOPEN_CLOEXEC) = 3 mount_setattr(-1, NULL, 0, NULL, 0) = -1 EINVAL (Invalid argument) ..... fsconfig(3, FSCONFIG_SET_STRING, "source", "/dev/pmem0", 0) = 0 fsconfig(3, FSCONFIG_SET_FLAG, "ro", NULL, 0) = 0 fsconfig(3, FSCONFIG_SET_FLAG, "norecovery", NULL, 0) = 0 fsconfig(3, FSCONFIG_CMD_CREATE, NULL, NULL, 0) = -1 EINVAL (Invalid argument) close(3) = 0 Showing that the actual mount instantiation (FSCONFIG_CMD_CREATE) is what threw out the error. During mount instantiation, we call xfs_fs_validate_params() which does: /* No recovery flag requires a read-only mount */ if (xfs_has_norecovery(mp) && !xfs_is_readonly(mp)) { xfs_warn(mp, "no-recovery mounts must be read-only."); return -EINVAL; } and xfs_is_readonly() checks internal mount flags for read only state. This state is set in xfs_init_fs_context() from the context superblock flag state: /* * Copy binary VFS mount flags we are interested in. */ if (fc->sb_flags & SB_RDONLY) set_bit(XFS_OPSTATE_READONLY, &mp->m_opstate); With the old mount API, all of the VFS specific superblock flags had already been parsed and set before xfs_init_fs_context() is called, so this all works fine. However, in the brave new fsopen/fsconfig world, xfs_init_fs_context() is called from fsopen() context, before any VFS superblock have been set or parsed. Hence if we use fsopen(), the internal XFS readonly state is *never set*. Hence anything that depends on xfs_is_readonly() actually returning true for read only mounts is broken if fsopen() has been used to mount the filesystem. Fix this by moving this internal state initialisation to xfs_fs_fill_super() before we attempt to validate the parameters that have been set prior to the FSCONFIG_CMD_CREATE call being made. Signed-off-by:Dave Chinner <dchinner@redhat.com> Fixes: 73e5fff9 ("xfs: switch to use the new mount-api") cc: stable@vger.kernel.org Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Chandan Babu R <chandanbabu@kernel.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
7f95f699
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