ocfs2: Validate metadata only when it's read from disk.

Add an optional validation hook to ocfs2_read_blocks().  Now the
validation function is only called when a block was actually read off of
disk.  It is not called when the buffer was in cache.

We add a buffer state bit BH_NeedsValidate to flag these buffers.  It
must always be one higher than the last JBD2 buffer state bit.

The dinode, dirblock, extent_block, and xattr_block validators are
lifted to this scheme directly.  The group_descriptor validator needs to
be split into two pieces.  The first part only needs the gd buffer and
is passed to ocfs2_read_block().  The second part requires the dinode as
well, and is called every time.  It's only 3 compares, so it's tiny.
This also allows us to clean up the non-fatal gd check used by resize.c.
It now has no magic argument.

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

1 files changed, 64 insertions, 27 deletions

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 766a00b2644..226fe21f260 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -145,14 +145,6 @@ 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);
 }
 
-int ocfs2_validate_group_descriptor(struct super_block *sb,
-                                    struct ocfs2_dinode *di,
-                                    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{                                                             \
                 if (clean_error)                                        \
@@ -161,6 +153,12 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
                         ocfs2_error(sb, fmt, ##__VA_ARGS__);            \
         } while (0)
 
+static int ocfs2_validate_gd_self(struct super_block *sb,
+                                  struct buffer_head *bh,
+                                  int clean_error)
+{
+        struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
         if (!OCFS2_IS_VALID_GROUP_DESC(gd)) {
                 do_error("Group descriptor #%llu has bad signature %.*s",
                          (unsigned long long)bh->b_blocknr, 7,
@@ -184,6 +182,35 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
                 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 "
+                         "claims that %u are free",
+                         (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 "
+                         "max bitmap bits of %u",
+                         (unsigned long long)bh->b_blocknr,
+                         le16_to_cpu(gd->bg_bits),
+                         8 * le16_to_cpu(gd->bg_size));
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int ocfs2_validate_gd_parent(struct super_block *sb,
+                                    struct ocfs2_dinode *di,
+                                    struct buffer_head *bh,
+                                    int clean_error)
+{
+        unsigned int max_bits;
+        struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+
         if (di->i_blkno != gd->bg_parent_dinode) {
                 do_error("Group descriptor #%llu has bad parent "
                          "pointer (%llu, expected %llu)",
@@ -209,26 +236,35 @@ int ocfs2_validate_group_descriptor(struct super_block *sb,
                 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 "
-                         "claims that %u are free",
-                         (unsigned long long)bh->b_blocknr,
-                         le16_to_cpu(gd->bg_bits),
-                         le16_to_cpu(gd->bg_free_bits_count));
-                return -EINVAL;
-        }
+        return 0;
+}
 
-        if (le16_to_cpu(gd->bg_bits) > (8 * le16_to_cpu(gd->bg_size))) {
-                do_error("Group descriptor #%llu has bit count %u but "
-                         "max bitmap bits of %u",
-                         (unsigned long long)bh->b_blocknr,
-                         le16_to_cpu(gd->bg_bits),
-                         8 * le16_to_cpu(gd->bg_size));
-                return -EINVAL;
-        }
 #undef do_error
 
-        return 0;
+/*
+ * This version only prints errors.  It does not fail the filesystem, and
+ * exists only for resize.
+ */
+int ocfs2_check_group_descriptor(struct super_block *sb,
+                                 struct ocfs2_dinode *di,
+                                 struct buffer_head *bh)
+{
+        int rc;
+
+        rc = ocfs2_validate_gd_self(sb, bh, 1);
+        if (!rc)
+                rc = ocfs2_validate_gd_parent(sb, di, bh, 1);
+
+        return rc;
+}
+
+static int ocfs2_validate_group_descriptor(struct super_block *sb,
+                                           struct buffer_head *bh)
+{
+        mlog(0, "Validating group descriptor %llu\n",
+             (unsigned long long)bh->b_blocknr);
+
+        return ocfs2_validate_gd_self(sb, bh, 0);
 }
 
 int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
@@ -237,11 +273,12 @@ int ocfs2_read_group_descriptor(struct inode *inode, struct ocfs2_dinode *di,
         int rc;
         struct buffer_head *tmp = *bh;
 
-        rc = ocfs2_read_block(inode, gd_blkno, &tmp);
+        rc = ocfs2_read_block(inode, gd_blkno, &tmp,
+                              ocfs2_validate_group_descriptor);
         if (rc)
                 goto out;
 
-        rc = ocfs2_validate_group_descriptor(inode->i_sb, di, tmp, 0);
+        rc = ocfs2_validate_gd_parent(inode->i_sb, di, tmp, 0);
         if (rc) {
                 brelse(tmp);
                 goto out;