[PATCH 6.6.x] btrfs: add cancellation points to trim loops

[David Sterba <dsterba@suse.com>]

From: Luca Stefani <luca.stefani.ge1@gmail.com>

There are reports that system cannot suspend due to running trim because
the task responsible for trimming the device isn't able to finish in
time, especially since we have a free extent discarding phase, which can
trim a lot of unallocated space. There are no limits on the trim size
(unlike the block group part).

Since trime isn't a critical call it can be interrupted at any time,
in such cases we stop the trim, report the amount of discarded bytes and
return an error.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219180
Link: https://bugzilla.suse.com/show_bug.cgi?id=1229737
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Luca Stefani <luca.stefani.ge1@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent-tree.c      | 7 ++++++-
 fs/btrfs/free-space-cache.c | 4 ++--
 fs/btrfs/free-space-cache.h | 7 +++++++
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b3680e1c7054..599407120513 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1319,6 +1319,11 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
 		start += bytes_to_discard;
 		bytes_left -= bytes_to_discard;
 		*discarded_bytes += bytes_to_discard;
+
+		if (btrfs_trim_interrupted()) {
+			ret = -ERESTARTSYS;
+			break;
+		}
 	}
 
 	return ret;
@@ -6094,7 +6099,7 @@ static int btrfs_trim_free_extents(struct btrfs_device *device, u64 *trimmed)
 		start += len;
 		*trimmed += bytes;
 
-		if (fatal_signal_pending(current)) {
+		if (btrfs_trim_interrupted()) {
 			ret = -ERESTARTSYS;
 			break;
 		}
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 3bcf4a30cad7..9a6ec9344c3e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3808,7 +3808,7 @@ static int trim_no_bitmap(struct btrfs_block_group *block_group,
 		if (async && *total_trimmed)
 			break;
 
-		if (fatal_signal_pending(current)) {
+		if (btrfs_trim_interrupted()) {
 			ret = -ERESTARTSYS;
 			break;
 		}
@@ -3999,7 +3999,7 @@ static int trim_bitmaps(struct btrfs_block_group *block_group,
 		}
 		block_group->discard_cursor = start;
 
-		if (fatal_signal_pending(current)) {
+		if (btrfs_trim_interrupted()) {
 			if (start != offset)
 				reset_trimming_bitmap(ctl, offset);
 			ret = -ERESTARTSYS;
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index 33b4da3271b1..bd80c7b2af96 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -6,6 +6,8 @@
 #ifndef BTRFS_FREE_SPACE_CACHE_H
 #define BTRFS_FREE_SPACE_CACHE_H
 
+#include <linux/freezer.h>
+
 /*
  * This is the trim state of an extent or bitmap.
  *
@@ -43,6 +45,11 @@ static inline bool btrfs_free_space_trimming_bitmap(
 	return (info->trim_state == BTRFS_TRIM_STATE_TRIMMING);
 }
 
+static inline bool btrfs_trim_interrupted(void)
+{
+	return fatal_signal_pending(current) || freezing(current);
+}
+
 /*
  * Deltas are an effective way to populate global statistics.  Give macro names
  * to make it clear what we're doing.  An example is discard_extents in
-- 
2.45.0