gfs2: add a helper function to get_log_header that can be used elsewhere

Move and re-order the error checks and hash/crc computations into another
function __get_log_header() so it can be used in scenarios where buffer_heads
are not being used for the log header.

Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

2 files changed, 35 insertions, 21 deletions

diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c
index b0717a074543..2dac43065382 100644
--- a/fs/gfs2/recovery.c
+++ b/fs/gfs2/recovery.c
@@ -120,6 +120,35 @@ void gfs2_revoke_clean(struct gfs2_jdesc *jd)
         }
 }
 
+int __get_log_header(struct gfs2_sbd *sdp, const struct gfs2_log_header *lh,
+                     unsigned int blkno, struct gfs2_log_header_host *head)
+{
+        u32 hash, crc;
+
+        if (lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
+            lh->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH) ||
+            (blkno && be32_to_cpu(lh->lh_blkno) != blkno))
+                return 1;
+
+        hash = crc32(~0, lh, LH_V1_SIZE - 4);
+        hash = ~crc32_le_shift(hash, 4); /* assume lh_hash is zero */
+
+        if (be32_to_cpu(lh->lh_hash) != hash)
+                return 1;
+
+        crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
+                     sdp->sd_sb.sb_bsize - LH_V1_SIZE - 4);
+
+        if ((lh->lh_crc != 0 && be32_to_cpu(lh->lh_crc) != crc))
+                return 1;
+
+        head->lh_sequence = be64_to_cpu(lh->lh_sequence);
+        head->lh_flags = be32_to_cpu(lh->lh_flags);
+        head->lh_tail = be32_to_cpu(lh->lh_tail);
+        head->lh_blkno = be32_to_cpu(lh->lh_blkno);
+
+        return 0;
+}
 /**
  * get_log_header - read the log header for a given segment
  * @jd: the journal
@@ -137,36 +166,18 @@ void gfs2_revoke_clean(struct gfs2_jdesc *jd)
 static int get_log_header(struct gfs2_jdesc *jd, unsigned int blk,
                           struct gfs2_log_header_host *head)
 {
-        struct gfs2_log_header *lh;
+        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
         struct buffer_head *bh;
-        u32 hash, crc;
         int error;
 
         error = gfs2_replay_read_block(jd, blk, &bh);
         if (error)
                 return error;
-        lh = (void *)bh->b_data;
-
-        hash = crc32(~0, lh, LH_V1_SIZE - 4);
-        hash = ~crc32_le_shift(hash, 4);  /* assume lh_hash is zero */
-
-        crc = crc32c(~0, (void *)lh + LH_V1_SIZE + 4,
-                     bh->b_size - LH_V1_SIZE - 4);
-
-        error = lh->lh_header.mh_magic != cpu_to_be32(GFS2_MAGIC) ||
-                lh->lh_header.mh_type != cpu_to_be32(GFS2_METATYPE_LH) ||
-                be32_to_cpu(lh->lh_blkno) != blk ||
-                be32_to_cpu(lh->lh_hash) != hash ||
-                (lh->lh_crc != 0 && be32_to_cpu(lh->lh_crc) != crc);
 
+        error = __get_log_header(sdp, (const struct gfs2_log_header *)bh->b_data,
+                                 blk, head);
         brelse(bh);
 
-        if (!error) {
-                head->lh_sequence = be64_to_cpu(lh->lh_sequence);
-                head->lh_flags = be32_to_cpu(lh->lh_flags);
-                head->lh_tail = be32_to_cpu(lh->lh_tail);
-                head->lh_blkno = be32_to_cpu(lh->lh_blkno);
-        }
         return error;
 }
 
diff --git a/fs/gfs2/recovery.h b/fs/gfs2/recovery.h
index 11fdfab4bf99..11d81248be85 100644
--- a/fs/gfs2/recovery.h
+++ b/fs/gfs2/recovery.h
@@ -31,6 +31,9 @@ extern int gfs2_find_jhead(struct gfs2_jdesc *jd,
                     struct gfs2_log_header_host *head);
 extern int gfs2_recover_journal(struct gfs2_jdesc *gfs2_jd, bool wait);
 extern void gfs2_recover_func(struct work_struct *work);
+extern int __get_log_header(struct gfs2_sbd *sdp,
+                            const struct gfs2_log_header *lh, unsigned int blkno,
+                            struct gfs2_log_header_host *head);
 
 #endif /* __RECOVERY_DOT_H__ */