ext4: Validate extent details only when read from the disk

Make sure we validate extent details only when read from the disk.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Thiemo Nagel <thiemo.nagel@ph.tum.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

3 files changed, 29 insertions, 7 deletions

diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 18cb67b2cbb..f0c3ec85bd4 100644
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -241,5 +241,6 @@ extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,
 extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,
                                                 ext4_lblk_t *, ext4_fsblk_t *);
 extern void ext4_ext_drop_refs(struct ext4_ext_path *);
+extern int ext4_ext_check_inode(struct inode *inode);
 #endif /* _EXT4_EXTENTS */
 
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ee40b7c52c8..ac77d8b8251 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -429,6 +429,11 @@ corrupted:
 #define ext4_ext_check(inode, eh, depth)        \
         __ext4_ext_check(__func__, inode, eh, depth)
 
+int ext4_ext_check_inode(struct inode *inode)
+{
+        return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode));
+}
+
 #ifdef EXT_DEBUG
 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
 {
@@ -631,9 +636,6 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
 
         eh = ext_inode_hdr(inode);
         depth = ext_depth(inode);
-        if (ext4_ext_check(inode, eh, depth))
-                return ERR_PTR(-EIO);
-
 
         /* account possible depth increase */
         if (!path) {
@@ -649,6 +651,8 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
         i = depth;
         /* walk through the tree */
         while (i) {
+                int need_to_validate = 0;
+
                 ext_debug("depth %d: num %d, max %d\n",
                           ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
 
@@ -657,10 +661,17 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
                 path[ppos].p_depth = i;
                 path[ppos].p_ext = NULL;
 
-                bh = sb_bread(inode->i_sb, path[ppos].p_block);
-                if (!bh)
+                bh = sb_getblk(inode->i_sb, path[ppos].p_block);
+                if (unlikely(!bh))
                         goto err;
-
+                if (!bh_uptodate_or_lock(bh)) {
+                        if (bh_submit_read(bh) < 0) {
+                                put_bh(bh);
+                                goto err;
+                        }
+                        /* validate the extent entries */
+                        need_to_validate = 1;
+                }
                 eh = ext_block_hdr(bh);
                 ppos++;
                 BUG_ON(ppos > depth);
@@ -668,7 +679,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
                 path[ppos].p_hdr = eh;
                 i--;
 
-                if (ext4_ext_check(inode, eh, i))
+                if (need_to_validate && ext4_ext_check(inode, eh, i))
                         goto err;
         }
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 25811507d2b..cd0399db0ef 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4345,6 +4345,16 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
         }
 
+        if (ei->i_flags & EXT4_EXTENTS_FL) {
+                /* Validate extent which is part of inode */
+                ret = ext4_ext_check_inode(inode);
+                if (ret) {
+                        brelse(bh);
+                        goto bad_inode;
+                }
+
+        }
+
         if (S_ISREG(inode->i_mode)) {
                 inode->i_op = &ext4_file_inode_operations;
                 inode->i_fop = &ext4_file_operations;