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Patch "Btrfs: fix truncate down when no_holes feature is enabled" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 3, 2017

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

Btrfs: fix truncate down when no_holes feature is enabled

to the 4.9-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:
btrfs-fix-truncate-down-when-no_holes-feature-is-enabled.patch
and it can be found in the queue-4.9 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 foo@baz Mon Jul 3 11:54:13 CEST 2017

From: Liu Bo <[email protected]>
Date: Thu, 1 Dec 2016 13:43:31 -0800
Subject: Btrfs: fix truncate down when no_holes feature is enabled

From: Liu Bo <[email protected]>

[ Upstream commit 91298eec05cd8d4e828cf7ee5d4a6334f70cf69a ]

For such a file mapping,

[0-4k][hole][8k-12k]

In NO_HOLES mode, we don't have the [hole] extent any more.
Commit c1aa45759e90 ("Btrfs: fix shrinking truncate when the no_holes feature is enabled")
fixed disk isize not being updated in NO_HOLES mode when data is not flushed.

However, even if data has been flushed, we can still have trouble in updating disk isize since we updated disk isize to 'start' of the last evicted extent.

---
 fs/btrfs/inode.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
fs/btrfs/inode.c +12 -1
@@ -4480,8 +4480,19 @@ search_again:
 		if (found_type > min_type) {
 			del_item = 1;
 		} else {
-			if (item_end < new_size)
+			if (item_end < new_size) {
+				/*
+				 * With NO_HOLES mode, for the following mapping
+				 *
+				 * [0-4k][hole][8k-12k]
+				 *
+				 * if truncating isize down to 6k, it ends up
+				 * isize being 8k.
+				 */
+				if (btrfs_fs_incompat(root->fs_info, NO_HOLES))
+					last_size = new_size;
 				break;
+			}
 			if (found_key.offset >= new_size)
 				del_item = 1;
 			else

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

queue-4.9/btrfs-fix-truncate-down-when-no_holes-feature-is-enabled.patch