[XFS] factor out xfs_read_agf helper

Add a helper to read the AGF header and perform basic verification.
Based on hunks from a larger patch from Dave Chinner.

(First sent on Juli 23rd)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
index f4a315390c61..f2e21817a226 100644
--- a/fs/xfs/xfs_ag.h
+++ b/fs/xfs/xfs_ag.h
@@ -91,6 +91,8 @@ typedef struct xfs_agf {
 #define XFS_AGF_BLOCK(mp)       XFS_HDR_BLOCK(mp, XFS_AGF_DADDR(mp))
 #define XFS_BUF_TO_AGF(bp)      ((xfs_agf_t *)XFS_BUF_PTR(bp))
 
+extern int xfs_read_agf(struct xfs_mount *mp, struct xfs_trans *tp,
+                        xfs_agnumber_t agno, int flags, struct xfs_buf **bpp);
 
 /*
  * Size of the unlinked inode hash table in the agi.