[ 3.8.y.z extended stable ] Patch "ext4: simplify truncation code in ext4_setattr()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ext4: simplify truncation code in ext4_setattr()

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 94c587e1982cd15329f843679458cc08b9e494f9 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack at suse.cz>
Date: Sat, 17 Aug 2013 10:07:17 -0400
Subject: ext4: simplify truncation code in ext4_setattr()

commit 5208386c501276df18fee464e21d3c58d2d79517 upstream.

Merge conditions in ext4_setattr() handling inode size changes, also
move ext4_begin_ordered_truncate() call somewhat earlier because it
simplifies error recovery in case of failure. Also add error handling in
case i_disksize update fails.

Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
[ kamal: backport to 3.8 (no ext4_journal_start context info) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/ext4/inode.c | 108 +++++++++++++++++++++++++-------------------------------
 1 file changed, 49 insertions(+), 59 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1ec8761..158145b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4422,7 +4422,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 		ext4_journal_stop(handle);
 	}

-	if (attr->ia_valid & ATTR_SIZE) {
+	if (attr->ia_valid & ATTR_SIZE && attr->ia_size != inode->i_size) {
+		handle_t *handle;
+		loff_t oldsize = inode->i_size;

 		if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -4430,72 +4432,60 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 			if (attr->ia_size > sbi->s_bitmap_maxbytes)
 				return -EFBIG;
 		}
-	}
-
-	if (S_ISREG(inode->i_mode) &&
-	    attr->ia_valid & ATTR_SIZE &&
-	    (attr->ia_size < inode->i_size)) {
-		handle_t *handle;
-
-		handle = ext4_journal_start(inode, 3);
-		if (IS_ERR(handle)) {
-			error = PTR_ERR(handle);
-			goto err_out;
-		}
-		if (ext4_handle_valid(handle)) {
-			error = ext4_orphan_add(handle, inode);
-			orphan = 1;
-		}
-		EXT4_I(inode)->i_disksize = attr->ia_size;
-		rc = ext4_mark_inode_dirty(handle, inode);
-		if (!error)
-			error = rc;
-		ext4_journal_stop(handle);
-
-		if (ext4_should_order_data(inode)) {
-			error = ext4_begin_ordered_truncate(inode,
+		if (S_ISREG(inode->i_mode) &&
+		    (attr->ia_size < inode->i_size)) {
+			if (ext4_should_order_data(inode)) {
+				error = ext4_begin_ordered_truncate(inode,
 							    attr->ia_size);
-			if (error) {
-				/* Do as much error cleanup as possible */
-				handle = ext4_journal_start(inode, 3);
-				if (IS_ERR(handle)) {
-					ext4_orphan_del(NULL, inode);
+				if (error)
 					goto err_out;
-				}
-				ext4_orphan_del(handle, inode);
-				orphan = 0;
-				ext4_journal_stop(handle);
+			}
+			handle = ext4_journal_start(inode, 3);
+			if (IS_ERR(handle)) {
+				error = PTR_ERR(handle);
+				goto err_out;
+			}
+			if (ext4_handle_valid(handle)) {
+				error = ext4_orphan_add(handle, inode);
+				orphan = 1;
+			}
+			EXT4_I(inode)->i_disksize = attr->ia_size;
+			rc = ext4_mark_inode_dirty(handle, inode);
+			if (!error)
+				error = rc;
+			ext4_journal_stop(handle);
+			if (error) {
+				ext4_orphan_del(NULL, inode);
 				goto err_out;
 			}
 		}
-	}

-	if (attr->ia_valid & ATTR_SIZE) {
-		if (attr->ia_size != inode->i_size) {
-			loff_t oldsize = inode->i_size;
-
-			i_size_write(inode, attr->ia_size);
-			/*
-			 * Blocks are going to be removed from the inode. Wait
-			 * for dio in flight.  Temporarily disable
-			 * dioread_nolock to prevent livelock.
-			 */
-			if (orphan) {
-				if (!ext4_should_journal_data(inode)) {
-					ext4_inode_block_unlocked_dio(inode);
-					inode_dio_wait(inode);
-					ext4_inode_resume_unlocked_dio(inode);
-				} else
-					ext4_wait_for_tail_page_commit(inode);
-			}
-			/*
-			 * Truncate pagecache after we've waited for commit
-			 * in data=journal mode to make pages freeable.
-			 */
-			truncate_pagecache(inode, oldsize, inode->i_size);
+		i_size_write(inode, attr->ia_size);
+		/*
+		 * Blocks are going to be removed from the inode. Wait
+		 * for dio in flight.  Temporarily disable
+		 * dioread_nolock to prevent livelock.
+		 */
+		if (orphan) {
+			if (!ext4_should_journal_data(inode)) {
+				ext4_inode_block_unlocked_dio(inode);
+				inode_dio_wait(inode);
+				ext4_inode_resume_unlocked_dio(inode);
+			} else
+				ext4_wait_for_tail_page_commit(inode);
 		}
-		ext4_truncate(inode);
+		/*
+		 * Truncate pagecache after we've waited for commit
+		 * in data=journal mode to make pages freeable.
+		 */
+		truncate_pagecache(inode, oldsize, inode->i_size);
 	}
+	/*
+	 * We want to call ext4_truncate() even if attr->ia_size ==
+	 * inode->i_size for cases like truncation of fallocated space
+	 */
+	if (attr->ia_valid & ATTR_SIZE)
+		ext4_truncate(inode);

 	if (!rc) {
 		setattr_copy(inode, attr);
--
1.8.1.2