Re: Errors reported by Coverity in ext3

[Amir Goldor <amir73il@users.sourceforge.net>]

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Thanks for your corrections.

Attached is a new patch against kernel 2.6.29.1.
I applied most of your corrections, see my comments inline.
Please review take #2.

Thanks,
Amir.

On Tue, Apr 21, 2009 at 1:14 AM, Andreas Dilger <adilger@sun.com> wrote:
>
> Thanks for the patch, unfortunately it is a NACK, since there are a few
> bugs in the error handling, and some additional cleanups that can be done.
>
> More comments inline.
>
>> @@ -2302,7 +2310,9 @@ static int ext3_rename (struct inode * o
>>               BUFFER_TRACE(new_bh, "get write access");
>> -             ext3_journal_get_write_access(handle, new_bh);
>> +             retval = ext3_journal_get_write_access(handle, new_bh);
>> +             if (retval)
>> +                     goto end_rename;
>
> Similarly, this also needs a "brelse(new_bh)" before "goto end_rename".

brelse(new_bh) as well as brelse(dir_bh) are called on end_rename.

>
>> @@ -2360,7 +2370,14 @@ static int ext3_rename (struct inode * o
>>       ext3_update_dx_flag(old_dir);
>>       if (dir_bh) {
>>               BUFFER_TRACE(dir_bh, "get_write_access");
>> +             retval = ext3_journal_get_write_access(handle, dir_bh);
>> +             if (retval) {
>> +                     ext3_warning(old_dir->i_sb, "ext3_rename",
>> +                                     "Updating new directory (%lu) parent link, %d, error=%d",
>> +                                     new_dir->i_ino, new_dir->i_nlink, retval);
>> +             }
>> +     }
>
> At this point, if we cannot get write access to the directory buffer, it
> is really a bit too late to do much about it.  It may make more sense to
> instead call ext3_journal_get_write_access() right after ext3_bread() is
> called dor this buffer, so that the error can be checked and the rename
> aborted before any changes are made.
>

good idea. I moved it up.

> Note also that there are some places where ext3_journal_dirty_metadata()
> are called in these same code paths, but the error is not checked by the
> caller.
>

true, but as with the case above, handling errors before the changes
are made is much easier,
and I am only aiming for 'best effort' in this patch.

[-- Attachment #2: ext3-namei-check-jbd-errors-2.6.29.1.patch --]
[-- Type: application/octet-stream, Size: 2552 bytes --]

diff -up linux-2.6.29.1.orig/fs/ext3/namei.c linux-2.6.29.1/fs/ext3/namei.c
--- linux-2.6.29.1.orig/fs/ext3/namei.c	2009-04-21 10:44:01.000000000 +0300
+++ linux-2.6.29.1/fs/ext3/namei.c	2009-04-21 11:35:12.000000000 +0300
@@ -1627,7 +1627,7 @@ static int ext3_delete_entry (handle_t *
 			      struct buffer_head * bh)
 {
 	struct ext3_dir_entry_2 * de, * pde;
-	int i;
+	int i, err;
 
 	i = 0;
 	pde = NULL;
@@ -1637,7 +1637,9 @@ static int ext3_delete_entry (handle_t *
 			return -EIO;
 		if (de == de_del)  {
 			BUFFER_TRACE(bh, "get_write_access");
-			ext3_journal_get_write_access(handle, bh);
+			err = ext3_journal_get_write_access(handle, bh);
+			if (err)
+				return err;
 			if (pde)
 				pde->rec_len = ext3_rec_len_to_disk(
 					ext3_rec_len_from_disk(pde->rec_len) +
@@ -1784,7 +1786,15 @@ retry:
 		goto out_stop;
 	}
 	BUFFER_TRACE(dir_block, "get_write_access");
-	ext3_journal_get_write_access(handle, dir_block);
+	err = ext3_journal_get_write_access(handle, dir_block);
+	if (err) {
+		drop_nlink(inode); /* is this nlink == 0? */
+		unlock_new_inode(inode);
+		ext3_mark_inode_dirty(handle, inode);
+		iput (inode);
+		brelse (dir_block);
+		goto out_stop;
+	}
 	de = (struct ext3_dir_entry_2 *) dir_block->b_data;
 	de->inode = cpu_to_le32(inode->i_ino);
 	de->name_len = 1;
@@ -2318,6 +2328,10 @@ static int ext3_rename (struct inode * o
 		if (!new_inode && new_dir!=old_dir &&
 				new_dir->i_nlink >= EXT3_LINK_MAX)
 			goto end_rename;
+		BUFFER_TRACE(dir_bh, "get_write_access");
+		retval = ext3_journal_get_write_access(handle, dir_bh);
+		if (retval)
+			goto end_rename;
 	}
 	if (!new_bh) {
 		retval = ext3_add_entry (handle, new_dentry, old_inode);
@@ -2325,7 +2339,9 @@ static int ext3_rename (struct inode * o
 			goto end_rename;
 	} else {
 		BUFFER_TRACE(new_bh, "get write access");
-		ext3_journal_get_write_access(handle, new_bh);
+		retval = ext3_journal_get_write_access(handle, new_bh);
+		if (retval)
+			goto end_rename;
 		new_de->inode = cpu_to_le32(old_inode->i_ino);
 		if (EXT3_HAS_INCOMPAT_FEATURE(new_dir->i_sb,
 					      EXT3_FEATURE_INCOMPAT_FILETYPE))
@@ -2382,8 +2398,6 @@ static int ext3_rename (struct inode * o
 	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
 	ext3_update_dx_flag(old_dir);
 	if (dir_bh) {
-		BUFFER_TRACE(dir_bh, "get_write_access");
-		ext3_journal_get_write_access(handle, dir_bh);
 		PARENT_INO(dir_bh->b_data) = cpu_to_le32(new_dir->i_ino);
 		BUFFER_TRACE(dir_bh, "call ext3_journal_dirty_metadata");
 		ext3_journal_dirty_metadata(handle, dir_bh);