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authorMikulas Patocka <mpatocka@redhat.com>2019-10-02 13:14:17 +0300
committerMike Snitzer <snitzer@redhat.com>2019-10-10 16:45:48 +0300
commita2f83e8b0c82c9500421a26c49eb198b25fcdea3 (patch)
treeff79e8472252dbd823a0bf9e86e336a7da63af1f /drivers/md/dm-snap.c
parent0a005856d35936e351cc20ff3de04499bd7ffbfd (diff)
downloadlinux-a2f83e8b0c82c9500421a26c49eb198b25fcdea3.tar.xz
dm snapshot: introduce account_start_copy() and account_end_copy()
This simple refactoring moves code for modifying the semaphore cow_count into separate functions to prepare for changes that will extend these methods to provide for a more sophisticated mechanism for COW throttling. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Nikos Tsironis <ntsironis@arrikto.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index f150f5c5492b..da3bd1794ee0 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1512,6 +1512,16 @@ static void snapshot_dtr(struct dm_target *ti)
kfree(s);
}
+static void account_start_copy(struct dm_snapshot *s)
+{
+ down(&s->cow_count);
+}
+
+static void account_end_copy(struct dm_snapshot *s)
+{
+ up(&s->cow_count);
+}
+
/*
* Flush a list of buffers.
*/
@@ -1732,7 +1742,7 @@ static void copy_callback(int read_err, unsigned long write_err, void *context)
rb_link_node(&pe->out_of_order_node, parent, p);
rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree);
}
- up(&s->cow_count);
+ account_end_copy(s);
}
/*
@@ -1756,7 +1766,7 @@ static void start_copy(struct dm_snap_pending_exception *pe)
dest.count = src.count;
/* Hand over to kcopyd */
- down(&s->cow_count);
+ account_start_copy(s);
dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe);
}
@@ -1776,7 +1786,7 @@ static void start_full_bio(struct dm_snap_pending_exception *pe,
pe->full_bio = bio;
pe->full_bio_end_io = bio->bi_end_io;
- down(&s->cow_count);
+ account_start_copy(s);
callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client,
copy_callback, pe);
@@ -1866,7 +1876,7 @@ static void zero_callback(int read_err, unsigned long write_err, void *context)
struct bio *bio = context;
struct dm_snapshot *s = bio->bi_private;
- up(&s->cow_count);
+ account_end_copy(s);
bio->bi_status = write_err ? BLK_STS_IOERR : 0;
bio_endio(bio);
}
@@ -1880,7 +1890,7 @@ static void zero_exception(struct dm_snapshot *s, struct dm_exception *e,
dest.sector = bio->bi_iter.bi_sector;
dest.count = s->store->chunk_size;
- down(&s->cow_count);
+ account_start_copy(s);
WARN_ON_ONCE(bio->bi_private);
bio->bi_private = s;
dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio);