Commit c4e0540d authored Jun 06, 2019 by Naohiro Aota Committed by David Sterba Jun 14, 2019

btrfs: start readahead also in seed devices



Currently, btrfs does not consult seed devices to start readahead. As a
result, if readahead zone is added to the seed devices, btrfs_reada_wait()
indefinitely wait for the reada_ctl to finish.

You can reproduce the hung by modifying btrfs/163 to have larger initial
file size (e.g. xfs_io pwrite 4M instead of current 256K).

Fixes: 7414a03f ("btrfs: initial readahead code and prototypes")
Cc: stable@vger.kernel.org # 3.2+: ce7791ff: Btrfs: fix race between readahead and device replace/removal
Cc: stable@vger.kernel.org # 3.2+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 8eaf40c0

fs/btrfs/reada.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -747,6 +747,7 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info)
		u64 total = 0;
		int i;

		again:
		do {
		enqueued = 0;
		mutex_lock(&fs_devices->device_list_mutex);
		@@ -758,6 +759,10 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info)
		mutex_unlock(&fs_devices->device_list_mutex);
		total += enqueued;
		} while (enqueued && total < 10000);
		if (fs_devices->seed) {
		fs_devices = fs_devices->seed;
		goto again;
		}

		if (enqueued == 0)
		return;

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