ocfs2: Wrap group descriptor reads in a dedicated function.

We have a clean call for validating group descriptors, but every place
that wants the always does a read_block()+validate() call pair.  Create
a toplevel ocfs2_read_group_descriptor() that does the right
thing.  This allows us to leverage the single call point later for
fancier handling.  We also add validation of gd->bg_generation against
the superblock and gd->bg_blkno against the block we thought we read.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

3 files changed, 78 insertions, 61 deletions

diff --git a/fs/ocfs2/resize.c b/fs/ocfs2/resize.c
index a2de32a317ad..252baff5eb84 100644
--- a/fs/ocfs2/resize.c
+++ b/fs/ocfs2/resize.c
@@ -330,20 +330,14 @@ int ocfs2_group_extend(struct inode * inode, int new_clusters)
         lgd_blkno = ocfs2_which_cluster_group(main_bm_inode,
                                               first_new_cluster - 1);
 
-        ret = ocfs2_read_block(main_bm_inode, lgd_blkno, &group_bh);
+        ret = ocfs2_read_group_descriptor(main_bm_inode, fe, lgd_blkno,
+                                          &group_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 goto out_unlock;
         }
-
         group = (struct ocfs2_group_desc *)group_bh->b_data;
 
-        ret = ocfs2_check_group_descriptor(inode->i_sb, fe, group);
-        if (ret) {
-                mlog_errno(ret);
-                goto out_unlock;
-        }
-
         cl_bpc = le16_to_cpu(fe->id2.i_chain.cl_bpc);
         if (le16_to_cpu(group->bg_bits) / cl_bpc + new_clusters >
                 le16_to_cpu(fe->id2.i_chain.cl_cpg)) {
@@ -400,7 +394,7 @@ static int ocfs2_check_new_group(struct inode *inode,
                 (struct ocfs2_group_desc *)group_bh->b_data;
         u16 cl_bpc = le16_to_cpu(di->id2.i_chain.cl_bpc);
 
-        ret = ocfs2_validate_group_descriptor(inode->i_sb, di, gd, 1);
+        ret = ocfs2_validate_group_descriptor(inode->i_sb, di, group_bh, 1);
         if (ret)
                 goto out;
 
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index ddba97dc06a0..797f509d7250 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -145,13 +145,13 @@ static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
         return (u32)le16_to_cpu(cl->cl_cpg) * (u32)le16_to_cpu(cl->cl_bpc);
 }
 
-/* somewhat more expensive than our other checks, so use sparingly. */
 int ocfs2_validate_group_descriptor(struct super_block *sb,
                                     struct ocfs2_dinode *di,
-                                    struct ocfs2_group_desc *gd,
+                                    struct buffer_head *bh,
                                     int clean_error)
 {
         unsigned int max_bits;
+        struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
 
 #define do_error(fmt, ...)                                              \
         do{                                                             \
@@ -162,16 +162,32 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
         } while (0)
 
         if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
-                do_error("Group Descriptor #%llu has bad signature %.*s",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno), 7,
+                do_error("Group descriptor #%llu has bad signature %.*s",
+                         (unsigned long long)bh->b_blocknr, 7,
                          gd->bg_signature);
                 return -EINVAL;
         }
 
+        if (le64_to_cpu(gd->bg_blkno) != bh->b_blocknr) {
+                do_error("Group descriptor #%llu has an invalid bg_blkno "
+                         "of %llu",
+                         (unsigned long long)bh->b_blocknr,
+                         (unsigned long long)le64_to_cpu(gd->bg_blkno));
+                return -EINVAL;
+        }
+
+        if (le32_to_cpu(gd->bg_generation) != OCFS2_SB(sb)->fs_generation) {
+                do_error("Group descriptor #%llu has an invalid "
+                         "fs_generation of #%u",
+                         (unsigned long long)bh->b_blocknr,
+                         le32_to_cpu(gd->bg_generation));
+                return -EINVAL;
+        }
+
         if (di->i_blkno != gd->bg_parent_dinode) {
-                do_error("Group descriptor # %llu has bad parent "
+                do_error("Group descriptor #%llu has bad parent "
                          "pointer (%llu, expected %llu)",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno),
+                         (unsigned long long)bh->b_blocknr,
                          (unsigned long long)le64_to_cpu(gd->bg_parent_dinode),
                          (unsigned long long)le64_to_cpu(di->i_blkno));
                 return -EINVAL;
@@ -179,33 +195,33 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
 
         max_bits = le16_to_cpu(di->id2.i_chain.cl_cpg) * le16_to_cpu(di->id2.i_chain.cl_bpc);
         if (le16_to_cpu(gd->bg_bits) > max_bits) {
-                do_error("Group descriptor # %llu has bit count of %u",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno),
+                do_error("Group descriptor #%llu has bit count of %u",
+                         (unsigned long long)bh->b_blocknr,
                          le16_to_cpu(gd->bg_bits));
                 return -EINVAL;
         }
 
         if (le16_to_cpu(gd->bg_chain) >=
             le16_to_cpu(di->id2.i_chain.cl_next_free_rec)) {
-                do_error("Group descriptor # %llu has bad chain %u",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno),
+                do_error("Group descriptor #%llu has bad chain %u",
+                         (unsigned long long)bh->b_blocknr,
                          le16_to_cpu(gd->bg_chain));
                 return -EINVAL;
         }
 
         if (le16_to_cpu(gd->bg_free_bits_count) > le16_to_cpu(gd->bg_bits)) {
-                do_error("Group descriptor # %llu has bit count %u but "
+                do_error("Group descriptor #%llu has bit count %u but "
                          "claims that %u are free",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno),
+                         (unsigned long long)bh->b_blocknr,
                          le16_to_cpu(gd->bg_bits),
                          le16_to_cpu(gd->bg_free_bits_count));
                 return -EINVAL;
         }
 
         if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
-                do_error("Group descriptor # %llu has bit count %u but "
+                do_error("Group descriptor #%llu has bit count %u but "
                          "max bitmap bits of %u",
-                         (unsigned long long)le64_to_cpu(gd->bg_blkno),
+                         (unsigned long long)bh->b_blocknr,
                          le16_to_cpu(gd->bg_bits),
                          8 * le16_to_cpu(gd->bg_size));
                 return -EINVAL;
@@ -215,6 +231,30 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
         return 0;
 }
 
+int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
+                                u64 gd_blkno, struct buffer_head **bh)
+{
+        int rc;
+        struct buffer_head *tmp = *bh;
+
+        rc = ocfs2_read_block(inode, gd_blkno, &tmp);
+        if (rc)
+                goto out;
+
+        rc = ocfs2_validate_group_descriptor(inode->i_sb, di, tmp, 0);
+        if (rc) {
+                brelse(tmp);
+                goto out;
+        }
+
+        /* If ocfs2_read_block() got us a new bh, pass it up. */
+        if (!*bh)
+                *bh = tmp;
+
+out:
+        return rc;
+}
+
 static int ocfs2_block_group_fill(handle_t *handle,
                                   struct inode *alloc_inode,
                                   struct buffer_head *bg_bh,
@@ -1177,21 +1217,17 @@ static int ocfs2_search_one_group(struct ocfs2_alloc_context *ac,
         u16 found;
         struct buffer_head *group_bh = NULL;
         struct ocfs2_group_desc *gd;
+        struct ocfs2_dinode *di = (struct ocfs2_dinode *)ac->ac_bh->b_data;
         struct inode *alloc_inode = ac->ac_inode;
 
-        ret = ocfs2_read_block(alloc_inode, gd_blkno, &group_bh);
+        ret = ocfs2_read_group_descriptor(alloc_inode, di, gd_blkno,
+                                          &group_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 return ret;
         }
 
         gd = (struct ocfs2_group_desc *) group_bh->b_data;
-        if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
-                OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, gd);
-                ret = -EIO;
-                goto out;
-        }
-
         ret = ac->ac_group_search(alloc_inode, group_bh, bits_wanted, min_bits,
                                   ac->ac_max_block, bit_off, &found);
         if (ret < 0) {
@@ -1248,19 +1284,14 @@ static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
              bits_wanted, chain,
              (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno);
 
-        status = ocfs2_read_block(alloc_inode,
-                                  le64_to_cpu(cl->cl_recs[chain].c_blkno),
-                                  &group_bh);
+        status = ocfs2_read_group_descriptor(alloc_inode, fe,
+                                             le64_to_cpu(cl->cl_recs[chain].c_blkno),
+                                             &group_bh);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
         bg = (struct ocfs2_group_desc *) group_bh->b_data;
-        status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
-        if (status) {
-                mlog_errno(status);
-                goto bail;
-        }
 
         status = -ENOSPC;
         /* for now, the chain search is a bit simplistic. We just use
@@ -1278,18 +1309,13 @@ static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
                 next_group = le64_to_cpu(bg->bg_next_group);
                 prev_group_bh = group_bh;
                 group_bh = NULL;
-                status = ocfs2_read_block(alloc_inode,
-                                          next_group, &group_bh);
+                status = ocfs2_read_group_descriptor(alloc_inode, fe,
+                                                     next_group, &group_bh);
                 if (status < 0) {
                         mlog_errno(status);
                         goto bail;
                 }
                 bg = (struct ocfs2_group_desc *) group_bh->b_data;
-                status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, bg);
-                if (status) {
-                        mlog_errno(status);
-                        goto bail;
-                }
         }
         if (status < 0) {
                 if (status != -ENOSPC)
@@ -1801,18 +1827,14 @@ int ocfs2_free_suballoc_bits(handle_t *handle,
              (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno, count,
              (unsigned long long)bg_blkno, start_bit);
 
-        status = ocfs2_read_block(alloc_inode, bg_blkno, &group_bh);
+        status = ocfs2_read_group_descriptor(alloc_inode, fe, bg_blkno,
+                                             &group_bh);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
-
         group = (struct ocfs2_group_desc *) group_bh->b_data;
-        status = ocfs2_check_group_descriptor(alloc_inode->i_sb, fe, group);
-        if (status) {
-                mlog_errno(status);
-                goto bail;
-        }
+
         BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits));
 
         status = ocfs2_block_group_clear_bits(handle, alloc_inode,
diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index 7adfcc478bdb..43de4fd826d3 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -164,23 +164,24 @@ void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac);
  * and return that block offset. */
 u64 ocfs2_which_cluster_group(struct inode *inode, u32 cluster);
 
-/* somewhat more expensive than our other checks, so use sparingly. */
 /*
  * By default, ocfs2_validate_group_descriptor() calls ocfs2_error() when it
  * finds a problem.  A caller that wants to check a group descriptor
  * without going readonly passes a nonzero clean_error.  This is only
- * resize, really.
+ * resize, really.  Everyone else should be using
+ * ocfs2_read_group_descriptor().
  */
 int ocfs2_validate_group_descriptor(struct super_block *sb,
                                     struct ocfs2_dinode *di,
-                                    struct ocfs2_group_desc *gd,
+                                    struct buffer_head *bh,
                                     int clean_error);
-static inline int ocfs2_check_group_descriptor(struct super_block *sb,
-                                               struct ocfs2_dinode *di,
-                                               struct ocfs2_group_desc *gd)
-{
-        return ocfs2_validate_group_descriptor(sb, di, gd, 0);
-}
+/*
+ * Read a group descriptor block into *bh.  If *bh is NULL, a bh will be
+ * allocated.  This is a cached read.  The descriptor will be validated with
+ * ocfs2_validate_group_descriptor().
+ */
+int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
+                                u64 gd_blkno, struct buffer_head **bh);
 
 int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_extent_tree *et,
                           u32 clusters_to_add, u32 extents_to_split,