linux-ext4 - [PATCH -V2 1/2] ext4: Add inode to the orphan list during block allocation failure

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Message-Id: <1244435715-6807-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Date:	Mon,  8 Jun 2009 10:05:14 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	cmm@...ibm.com, tytso@....edu, sandeen@...hat.com
Cc:	linux-ext4@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Jan Kara <jack@...e.cz>
Subject: [PATCH -V2 1/2] ext4: Add inode to the orphan list during block allocation failure

We should add inode to the orphan list in the same transaction
as block allocation. This ensures that if we crash after a failed
block allocation and before we do a vmtruncate we don't leak block
(ie block marked as used in bitmap but not claimed by the inode).

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
CC:  Jan Kara <jack@...e.cz>
---
 fs/ext4/inode.c |   22 ++++++++++++++++++++--
 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 00ebc99..820cb58 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1459,7 +1459,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 				struct page **pagep, void **fsdata)
 {
 	struct inode *inode = mapping->host;
-	int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
+	int ret, needed_blocks;
 	handle_t *handle;
 	int retries = 0;
 	struct page *page;
@@ -1470,6 +1470,11 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 		   "dev %s ino %lu pos %llu len %u flags %u",
 		   inode->i_sb->s_id, inode->i_ino,
 		   (unsigned long long) pos, len, flags);
+	/*
+	 * Reserve one block more for addition to orphan list in case
+	 * we allocate blocks but write fails for some reason
+	 */
+	needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
  	index = pos >> PAGE_CACHE_SHIFT;
 	from = pos & (PAGE_CACHE_SIZE - 1);
 	to = from + len;
@@ -1503,14 +1508,20 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 
 	if (ret) {
 		unlock_page(page);
-		ext4_journal_stop(handle);
 		page_cache_release(page);
 		/*
 		 * block_write_begin may have instantiated a few blocks
 		 * outside i_size.  Trim these off again. Don't need
 		 * i_size_read because we hold i_mutex.
+		 *
+		 * Add inode to orphan list in case we crash before
+		 * truncate finishes
 		 */
 		if (pos + len > inode->i_size)
+			ext4_orphan_add(handle, inode);
+
+		ext4_journal_stop(handle);
+		if (pos + len > inode->i_size)
 			vmtruncate(inode, inode->i_size);
 	}
 
@@ -1519,6 +1530,13 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 out:
 	if (ret)
 		block_unlock_hole_extend(inode);
+	/*
+	 * if vmtruncate failed to remove the inode from
+	 * orphan list remove ourself
+	 */
+	if (inode->i_nlink)
+		ext4_orphan_del(NULL, inode);
+
 	return ret;
 }
 
-- 
1.6.3.1.244.gf9275

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