[PATCH v6 2/2] btrfs: Don't block system suspend during fstrim

[Luca Stefani]

Sometimes the system isn't able to suspend 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, and there is no
limits on the trim size (unlike the block group part).

Since discard 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 failure.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219180
Link: https://bugzilla.suse.com/show_bug.cgi?id=1229737
Signed-off-by: Luca Stefani <luca.stefani.ge1@xxxxxxxxx>
---
 fs/btrfs/extent-tree.c      | 7 ++++++-
 fs/btrfs/free-space-cache.c | 4 ++--
 fs/btrfs/free-space-cache.h | 6 ++++++
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ad70548d1f72..d9f511babd89 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1316,6 +1316,11 @@ 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;
@@ -6470,7 +6475,7 @@ 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 eaa1dbd31352..f4bcb2530660 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3809,7 +3809,7 @@ 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;
 		}
@@ -4000,7 +4000,7 @@ 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 83774bfd7b3b..9f1dbfdee8ca 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -10,6 +10,7 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
+#include <linux/freezer.h>
 #include "fs.h"
 
 struct inode;
@@ -56,6 +57,11 @@ 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
-- 
2.46.0