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Patch "ocfs2: fstrim: Fix start offset of first cluster group during fstrim" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Nov 5, 2017

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This is a note to let you know that I've just added the patch titled

ocfs2: fstrim: Fix start offset of first cluster group during fstrim

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ocfs2-fstrim-fix-start-offset-of-first-cluster-group-during-fstrim.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 105ddc93f06ebe3e553f58563d11ed63dbcd59f0 Mon Sep 17 00:00:00 2001

From: Ashish Samant <[email protected]>
Date: Thu, 2 Nov 2017 15:59:37 -0700
Subject: ocfs2: fstrim: Fix start offset of first cluster group during fstrim

From: Ashish Samant <[email protected]>

commit 105ddc93f06ebe3e553f58563d11ed63dbcd59f0 upstream.

The first cluster group descriptor is not stored at the start of the group but at an offset from the start. We need to take this into account while doing fstrim on the first cluster group. Otherwise we will wrongly start fstrim a few blocks after the desired start block and the range can cross over into the next cluster group and zero out the group descriptor there. This can cause filesytem corruption that cannot be fixed by fsck.

Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ashish Samant <[email protected]>
Reviewed-by Junxiao Bi <[email protected]>
Reviewed-by Joseph Qi <[email protected]>
Cc Mark Fasheh <[email protected]>
Cc Joel Becker <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 fs/ocfs2/alloc.c |   24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)
fs/ocfs2/alloc.c +18 -6
@@ -7270,13 +7270,24 @@ out:
 
 static int ocfs2_trim_extent(struct super_block *sb,
 			     struct ocfs2_group_desc *gd,
-			     u32 start, u32 count)
+			     u64 group, u32 start, u32 count)
 {
 	u64 discard, bcount;
+	struct ocfs2_super *osb = OCFS2_SB(sb);
 
 	bcount = ocfs2_clusters_to_blocks(sb, count);
-	discard = le64_to_cpu(gd->bg_blkno) +
-			ocfs2_clusters_to_blocks(sb, start);
+	discard = ocfs2_clusters_to_blocks(sb, start);
+
+	/*
+	 * For the first cluster group, the gd->bg_blkno is not at the start
+	 * of the group, but at an offset from the start. If we add it while
+	 * calculating discard for first group, we will wrongly start fstrim a
+	 * few blocks after the desried start block and the range can cross
+	 * over into the next cluster group. So, add it only if this is not
+	 * the first cluster group.
+	 */
+	if (group != osb->first_cluster_group_blkno)
+		discard += le64_to_cpu(gd->bg_blkno);
 
 	trace_ocfs2_trim_extent(sb, (unsigned long long)discard, bcount);
 

@@ -7284,7 +7295,7 @@ static int ocfs2_trim_extent(struct supe
 }
 
 static int ocfs2_trim_group(struct super_block *sb,
-			    struct ocfs2_group_desc *gd,
+			    struct ocfs2_group_desc *gd, u64 group,
 			    u32 start, u32 max, u32 minbits)
 {
 	int ret = 0, count = 0, next;

@@ -7303,7 +7314,7 @@ static int ocfs2_trim_group(struct super
 		next = ocfs2_find_next_bit(bitmap, max, start);
 
 		if ((next - start) >= minbits) {
-			ret = ocfs2_trim_extent(sb, gd,
+			ret = ocfs2_trim_extent(sb, gd, group,
 						start, next - start);
 			if (ret < 0) {
 				mlog_errno(ret);

@@ -7401,7 +7412,8 @@ int ocfs2_trim_fs(struct super_block *sb
 		}
 
 		gd = (struct ocfs2_group_desc *)gd_bh->b_data;
-		cnt = ocfs2_trim_group(sb, gd, first_bit, last_bit, minlen);
+		cnt = ocfs2_trim_group(sb, gd, group,
+				       first_bit, last_bit, minlen);
 		brelse(gd_bh);
 		gd_bh = NULL;
 		if (cnt < 0) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/ocfs2-fstrim-fix-start-offset-of-first-cluster-group-during-fstrim.patch