3.15-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dave Chinner <[email protected]> commit 556b8883cfac3d3203557e161ea8005f8b5479b2 upstream. Commit daba542 ("xfs: skip verification on initial "guess" superblock read") dropped the use of a verifier for the initial superblock read so we can probe the sector size of the filesystem stored in the superblock. It, however, now fails to validate that what was read initially is actually an XFS superblock and hence will fail the sector size check and return ENOSYS. This causes probe-based mounts to fail because it expects XFS to return EINVAL when it doesn't recognise the superblock format. Reported-by: Plamen Petrov <[email protected]> Tested-by: Plamen Petrov <[email protected]> Signed-off-by: Dave Chinner <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Dave Chinner <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/xfs/xfs_mount.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -323,8 +323,19 @@ reread: /* * Initialize the mount structure from the superblock. */ - xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp)); - xfs_sb_quota_from_disk(&mp->m_sb); + xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp)); + xfs_sb_quota_from_disk(sbp); + + /* + * If we haven't validated the superblock, do so now before we try + * to check the sector size and reread the superblock appropriately. + */ + if (sbp->sb_magicnum != XFS_SB_MAGIC) { + if (loud) + xfs_warn(mp, "Invalid superblock magic number"); + error = EINVAL; + goto release_buf; + } /* * We must be able to do sector-sized and sector-aligned IO. @@ -337,11 +348,11 @@ reread: goto release_buf; } - /* - * Re-read the superblock so the buffer is correctly sized, - * and properly verified. - */ if (buf_ops == NULL) { + /* + * Re-read the superblock so the buffer is correctly sized, + * and properly verified. + */ xfs_buf_relse(bp); sector_size = sbp->sb_sectsize; buf_ops = loud ? &xfs_sb_buf_ops : &xfs_sb_quiet_buf_ops; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
