jbd2: Fix oops in jbd2_journal_file_inode()

Commit 0713ed0cde76438d05849f1537d3aab46e099475 added
jbd2_journal_file_inode() call into ext4_block_zero_page_range().
However that function gets called from truncate path and thus inode
needn't have jinode attached - that happens in ext4_file_open() but
the file needn't be ever open since mount. Calling
jbd2_journal_file_inode() without jinode attached results in the oops.

We fix the problem by attaching jinode to inode also in ext4_truncate()
and ext4_punch_hole() when we are going to zero out partial blocks.

Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

3 files changed, 48 insertions, 17 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index b577e45425b0..0ab26fbf3380 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2086,6 +2086,7 @@ extern int  ext4_sync_inode(handle_t *, struct inode *);
 extern void ext4_dirty_inode(struct inode *, int);
 extern int ext4_change_inode_journal_flag(struct inode *, int);
 extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
+extern int ext4_inode_attach_jinode(struct inode *inode);
 extern int ext4_can_truncate(struct inode *inode);
 extern void ext4_truncate(struct inode *);
 extern int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 6f4cc567c382..319c9d26279a 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -219,7 +219,6 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 {
         struct super_block *sb = inode->i_sb;
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-        struct ext4_inode_info *ei = EXT4_I(inode);
         struct vfsmount *mnt = filp->f_path.mnt;
         struct path path;
         char buf[64], *cp;
@@ -259,22 +258,10 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
          * Set up the jbd2_inode if we are opening the inode for
          * writing and the journal is present
          */
-        if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
-                struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);
-
-                spin_lock(&inode->i_lock);
-                if (!ei->jinode) {
-                        if (!jinode) {
-                                spin_unlock(&inode->i_lock);
-                                return -ENOMEM;
-                        }
-                        ei->jinode = jinode;
-                        jbd2_journal_init_jbd_inode(ei->jinode, inode);
-                        jinode = NULL;
-                }
-                spin_unlock(&inode->i_lock);
-                if (unlikely(jinode != NULL))
-                        jbd2_free_inode(jinode);
+        if (filp->f_mode & FMODE_WRITE) {
+                int ret = ext4_inode_attach_jinode(inode);
+                if (ret < 0)
+                        return ret;
         }
         return dquot_file_open(inode, filp);
 }
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index dd32a2eacd0d..c2ca04e67a4f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3533,6 +3533,18 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
                    offset;
         }
 
+        if (offset & (sb->s_blocksize - 1) ||
+            (offset + length) & (sb->s_blocksize - 1)) {
+                /*
+                 * Attach jinode to inode for jbd2 if we do any zeroing of
+                 * partial block
+                 */
+                ret = ext4_inode_attach_jinode(inode);
+                if (ret < 0)
+                        goto out_mutex;
+
+        }
+
         first_block_offset = round_up(offset, sb->s_blocksize);
         last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
 
@@ -3601,6 +3613,31 @@ out_mutex:
         return ret;
 }
 
+int ext4_inode_attach_jinode(struct inode *inode)
+{
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        struct jbd2_inode *jinode;
+
+        if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
+                return 0;
+
+        jinode = jbd2_alloc_inode(GFP_KERNEL);
+        spin_lock(&inode->i_lock);
+        if (!ei->jinode) {
+                if (!jinode) {
+                        spin_unlock(&inode->i_lock);
+                        return -ENOMEM;
+                }
+                ei->jinode = jinode;
+                jbd2_journal_init_jbd_inode(ei->jinode, inode);
+                jinode = NULL;
+        }
+        spin_unlock(&inode->i_lock);
+        if (unlikely(jinode != NULL))
+                jbd2_free_inode(jinode);
+        return 0;
+}
+
 /*
  * ext4_truncate()
  *
@@ -3661,6 +3698,12 @@ void ext4_truncate(struct inode *inode)
                         return;
         }
 
+        /* If we zero-out tail of the page, we have to create jinode for jbd2 */
+        if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
+                if (ext4_inode_attach_jinode(inode) < 0)
+                        return;
+        }
+
         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                 credits = ext4_writepage_trans_blocks(inode);
         else