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diff -up util-linux-2.23.2/libblkid/src/superblocks/xfs.c.kzak util-linux-2.23.2/libblkid/src/superblocks/xfs.c
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--- util-linux-2.23.2/libblkid/src/superblocks/xfs.c.kzak	2014-09-24 10:59:39.548315524 +0200
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+++ util-linux-2.23.2/libblkid/src/superblocks/xfs.c	2014-09-24 11:02:55.595186026 +0200
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@@ -20,20 +20,143 @@
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 #include "superblocks.h"
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 struct xfs_super_block {
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-	unsigned char	xs_magic[4];
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-	uint32_t	xs_blocksize;
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-	uint64_t	xs_dblocks;
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-	uint64_t	xs_rblocks;
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-	uint32_t	xs_dummy1[2];
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-	unsigned char	xs_uuid[16];
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-	uint32_t	xs_dummy2[15];
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-	char		xs_fname[12];
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-	uint32_t	xs_dummy3[2];
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-	uint64_t	xs_icount;
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-	uint64_t	xs_ifree;
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-	uint64_t	xs_fdblocks;
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+	uint32_t	sb_magicnum;	/* magic number == XFS_SB_MAGIC */
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+	uint32_t	sb_blocksize;	/* logical block size, bytes */
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+	uint64_t	sb_dblocks;	/* number of data blocks */
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+	uint64_t	sb_rblocks;	/* number of realtime blocks */
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+	uint64_t	sb_rextents;	/* number of realtime extents */
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+	unsigned char	sb_uuid[16];	/* file system unique id */
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+	uint64_t	sb_logstart;	/* starting block of log if internal */
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+	uint64_t	sb_rootino;	/* root inode number */
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+	uint64_t	sb_rbmino;	/* bitmap inode for realtime extents */
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+	uint64_t	sb_rsumino;	/* summary inode for rt bitmap */
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+	uint32_t	sb_rextsize;	/* realtime extent size, blocks */
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+	uint32_t	sb_agblocks;	/* size of an allocation group */
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+	uint32_t	sb_agcount;	/* number of allocation groups */
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+	uint32_t	sb_rbmblocks;	/* number of rt bitmap blocks */
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+	uint32_t	sb_logblocks;	/* number of log blocks */
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+
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+	uint16_t	sb_versionnum;	/* header version == XFS_SB_VERSION */
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+	uint16_t	sb_sectsize;	/* volume sector size, bytes */
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+	uint16_t	sb_inodesize;	/* inode size, bytes */
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+	uint16_t	sb_inopblock;	/* inodes per block */
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+	char		sb_fname[12];	/* file system name */
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+	uint8_t		sb_blocklog;	/* log2 of sb_blocksize */
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+	uint8_t		sb_sectlog;	/* log2 of sb_sectsize */
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+	uint8_t		sb_inodelog;	/* log2 of sb_inodesize */
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+	uint8_t		sb_inopblog;	/* log2 of sb_inopblock */
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+	uint8_t		sb_agblklog;	/* log2 of sb_agblocks (rounded up) */
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+	uint8_t		sb_rextslog;	/* log2 of sb_rextents */
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+	uint8_t		sb_inprogress;	/* mkfs is in progress, don't mount */
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+	uint8_t		sb_imax_pct;	/* max % of fs for inode space */
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+					/* statistics */
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+	uint64_t	sb_icount;	/* allocated inodes */
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+	uint64_t	sb_ifree;	/* free inodes */
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+	uint64_t	sb_fdblocks;	/* free data blocks */
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+	uint64_t	sb_frextents;	/* free realtime extents */
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+
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+	/* this is not all... but enough for libblkid */
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+
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 } __attribute__((packed));
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+#define XFS_MIN_BLOCKSIZE_LOG	9	/* i.e. 512 bytes */
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+#define XFS_MAX_BLOCKSIZE_LOG	16	/* i.e. 65536 bytes */
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+#define XFS_MIN_BLOCKSIZE	(1 << XFS_MIN_BLOCKSIZE_LOG)
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+#define XFS_MAX_BLOCKSIZE	(1 << XFS_MAX_BLOCKSIZE_LOG)
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+#define XFS_MIN_SECTORSIZE_LOG	9	/* i.e. 512 bytes */
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+#define XFS_MAX_SECTORSIZE_LOG	15	/* i.e. 32768 bytes */
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+#define XFS_MIN_SECTORSIZE	(1 << XFS_MIN_SECTORSIZE_LOG)
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+#define XFS_MAX_SECTORSIZE	(1 << XFS_MAX_SECTORSIZE_LOG)
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+
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+#define	XFS_DINODE_MIN_LOG	8
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+#define	XFS_DINODE_MAX_LOG	11
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+#define	XFS_DINODE_MIN_SIZE	(1 << XFS_DINODE_MIN_LOG)
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+#define	XFS_DINODE_MAX_SIZE	(1 << XFS_DINODE_MAX_LOG)
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+
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+#define	XFS_MAX_RTEXTSIZE	(1024 * 1024 * 1024)	/* 1GB */
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+#define	XFS_DFL_RTEXTSIZE	(64 * 1024)	        /* 64kB */
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+#define	XFS_MIN_RTEXTSIZE	(4 * 1024)		/* 4kB */
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+
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+#define XFS_MIN_AG_BLOCKS	64
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+#define XFS_MAX_DBLOCKS(s) ((uint64_t)(s)->sb_agcount * (s)->sb_agblocks)
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+#define XFS_MIN_DBLOCKS(s) ((uint64_t)((s)->sb_agcount - 1) *	\
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+			 (s)->sb_agblocks + XFS_MIN_AG_BLOCKS)
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+
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+
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+static void sb_from_disk(struct xfs_super_block *from,
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+			 struct xfs_super_block *to)
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+{
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+
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+	to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
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+	to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
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+	to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
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+	to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
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+	to->sb_rextents = be64_to_cpu(from->sb_rextents);
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+	to->sb_logstart = be64_to_cpu(from->sb_logstart);
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+	to->sb_rootino = be64_to_cpu(from->sb_rootino);
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+	to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
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+	to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
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+	to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
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+	to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
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+	to->sb_agcount = be32_to_cpu(from->sb_agcount);
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+	to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
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+	to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
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+	to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
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+	to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
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+	to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
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+	to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
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+	to->sb_blocklog = from->sb_blocklog;
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+	to->sb_sectlog = from->sb_sectlog;
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+	to->sb_inodelog = from->sb_inodelog;
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+	to->sb_inopblog = from->sb_inopblog;
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+	to->sb_agblklog = from->sb_agblklog;
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+	to->sb_rextslog = from->sb_rextslog;
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+	to->sb_inprogress = from->sb_inprogress;
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+	to->sb_imax_pct = from->sb_imax_pct;
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+	to->sb_icount = be64_to_cpu(from->sb_icount);
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+	to->sb_ifree = be64_to_cpu(from->sb_ifree);
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+	to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
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+	to->sb_frextents = be64_to_cpu(from->sb_frextents);
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+}
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+
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+static int xfs_verify_sb(struct xfs_super_block *ondisk)
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+{
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+	struct xfs_super_block sb, *sbp = &sb;
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+
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+	/* beXX_to_cpu(), but don't convert UUID and fsname! */
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+	sb_from_disk(ondisk, sbp);
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+
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+	/* sanity checks, we don't want to rely on magic string only */
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+	if (sbp->sb_agcount <= 0					||
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+	    sbp->sb_sectsize < XFS_MIN_SECTORSIZE			||
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+	    sbp->sb_sectsize > XFS_MAX_SECTORSIZE			||
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+	    sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG			||
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+	    sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG			||
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+	    sbp->sb_sectsize != (1 << sbp->sb_sectlog)			||
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+	    sbp->sb_blocksize < XFS_MIN_BLOCKSIZE			||
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+	    sbp->sb_blocksize > XFS_MAX_BLOCKSIZE			||
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+	    sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG			||
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+	    sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG			||
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+	    sbp->sb_blocksize != (1 << sbp->sb_blocklog)		||
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+	    sbp->sb_inodesize < XFS_DINODE_MIN_SIZE			||
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+	    sbp->sb_inodesize > XFS_DINODE_MAX_SIZE			||
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+	    sbp->sb_inodelog < XFS_DINODE_MIN_LOG			||
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+	    sbp->sb_inodelog > XFS_DINODE_MAX_LOG			||
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+	    sbp->sb_inodesize != (1 << sbp->sb_inodelog)		||
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+	    (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)	||
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+	    (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)	||
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+	    (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)	||
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+	    (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */)	||
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+	    sbp->sb_dblocks == 0					||
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+	    sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)			||
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+	    sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))
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+		return 0;
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+
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+	/* TODO: version 5 has also checksum CRC32, maybe we can check it too */
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+
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+	return 1;
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+}
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+
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 static int probe_xfs(blkid_probe pr, const struct blkid_idmag *mag)
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 {
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 	struct xfs_super_block *xs;
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@@ -42,10 +165,13 @@ static int probe_xfs(blkid_probe pr, con
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 	if (!xs)
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 		return errno ? -errno : 1;
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-	if (strlen(xs->xs_fname))
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-		blkid_probe_set_label(pr, (unsigned char *) xs->xs_fname,
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-				sizeof(xs->xs_fname));
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-	blkid_probe_set_uuid(pr, xs->xs_uuid);
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+	if (!xfs_verify_sb(xs))
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+		return 1;
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+
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+	if (strlen(xs->sb_fname))
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+		blkid_probe_set_label(pr, (unsigned char *) xs->sb_fname,
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+				sizeof(xs->sb_fname));
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+	blkid_probe_set_uuid(pr, xs->sb_uuid);
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 	return 0;
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 }
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