linux-ext4 - Re: [PATCH] ext4: Set directory link count to zero if we fail to create the directory.

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Date:	Fri, 15 Feb 2008 14:23:30 -0500
From:	Theodore Tso <tytso@....EDU>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:	cmm@...ibm.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: Set directory link count to zero if we fail to
	create the directory.

I've replaced this patch with the following (see attached).  The
changes to the patch from Aneesh's original one are:

1) Replace the patch description with one that describes what is going
   on at a higher level.  (Always write with a deep sympathy for the
   reader, who will be reading the description as part of "git log".
   So mention that the problem was in ext4_mkdir, and the
   circumstances in which it would occur.)

2) The error handling code was duplicated later in the function
   (although in a slightly more efficient fashion; since we *know* the
   newly created inode has an inode->i_nlink of 1, it's easier just to
   set i_nlink to zero)

3) Replace the inode->i_nlink = 0 with the higher level equivalent
   inline function, clear_nlink(inode).

						- Ted

ext4: Don't leave behind a half-created inode if ext4_mkdir() fails

From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>

If ext4_mkdir() fails to allocate the initial block for the directory,
don't leave behind a half-created directory inode with the link count
left at one.  This was caused by an inappropriate call to ext4_dec_count().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@...ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a9347fb..7970e81 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1804,12 +1804,8 @@ retry:
 	inode->i_fop = &ext4_dir_operations;
 	inode->i_size = EXT4_I(inode)->i_disksize = inode->i_sb->s_blocksize;
 	dir_block = ext4_bread (handle, inode, 0, 1, &err);
-	if (!dir_block) {
-		ext4_dec_count(handle, inode); /* is this nlink == 0? */
-		ext4_mark_inode_dirty(handle, inode);
-		iput (inode);
-		goto out_stop;
-	}
+	if (!dir_block)
+		goto out_clear_inode;
 	BUFFER_TRACE(dir_block, "get_write_access");
 	ext4_journal_get_write_access(handle, dir_block);
 	de = (struct ext4_dir_entry_2 *) dir_block->b_data;
@@ -1832,7 +1828,8 @@ retry:
 	ext4_mark_inode_dirty(handle, inode);
 	err = ext4_add_entry (handle, dentry, inode);
 	if (err) {
-		inode->i_nlink = 0;
+	out_clear_inode:
+		clear_nlink(inode);
 		ext4_mark_inode_dirty(handle, inode);
 		iput (inode);
 		goto out_stop;
-
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