ocfs2: Wrap inode block reads in a dedicated function.

The ocfs2 code currently reads inodes off disk with a simple
ocfs2_read_block() call.  Each place that does this has a different set
of sanity checks it performs.  Some check only the signature.  A couple
validate the block number (the block read vs di->i_blkno).  A couple
others check for VALID_FL.  Only one place validates i_fs_generation.  A
couple check nothing.  Even when an error is found, they don't all do
the same thing.

We wrap inode reading into ocfs2_read_inode_block().  This will validate
all the above fields, going readonly if they are invalid (they never
should be).  ocfs2_read_inode_block_full() is provided for the places
that want to pass read_block flags.  Every caller is passing a struct
inode with a valid ip_blkno, so we don't need a separate blkno argument
either.

We will remove the validation checks from the rest of the code in a
later commit, as they are no longer necessary.

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

1 files changed, 14 insertions, 2 deletions

diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 2f37af9bcc4a..b79c371a9d27 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -128,8 +128,8 @@ struct inode *ocfs2_iget(struct ocfs2_super *osb, u64 feoff, unsigned flags,
                          int sysfile_type);
 int ocfs2_inode_init_private(struct inode *inode);
 int ocfs2_inode_revalidate(struct dentry *dentry);
-int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
-                         int create_ino);
+void ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
+                          int create_ino);
 void ocfs2_read_inode(struct inode *inode);
 void ocfs2_read_inode2(struct inode *inode, void *opaque);
 ssize_t ocfs2_rw_direct(int rw, struct file *filp, char *buf,
@@ -153,4 +153,16 @@ static inline blkcnt_t ocfs2_inode_sector_count(struct inode *inode)
         return (blkcnt_t)(OCFS2_I(inode)->ip_clusters << c_to_s_bits);
 }
 
+/* Validate that a bh contains a valid inode */
+int ocfs2_validate_inode_block(struct super_block *sb,
+                               struct buffer_head *bh);
+/*
+ * Read an inode block into *bh.  If *bh is NULL, a bh will be allocated.
+ * This is a cached read.  The inode will be validated with
+ * ocfs2_validate_inode_block().
+ */
+int ocfs2_read_inode_block(struct inode *inode, struct buffer_head **bh);
+/* The same, but can be passed OCFS2_BH_* flags */
+int ocfs2_read_inode_block_full(struct inode *inode, struct buffer_head **bh,
+                                int flags);
 #endif /* OCFS2_INODE_H */