UBI: Fastmap: Locking updates
a) Rename ubi->fm_sem to ubi->fm_eba_sem as this semaphore
protects EBA changes.
b) Turn ubi->fm_mutex into a rw semaphore. It will still serialize
fastmap writes but also ensures that ubi_wl_put_peb() is not
interrupted by a fastmap write. We use a rw semaphore to allow
ubi_wl_put_peb() still to be executed in parallel if no fastmap
write is happening.
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 749e2e4..2cf2506 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -800,7 +800,7 @@
__be32 crc, tmp_crc;
unsigned long long sqnum = 0;
- mutex_lock(&ubi->fm_mutex);
+ down_write(&ubi->fm_protect);
memset(ubi->fm_buf, 0, ubi->fm_size);
fmsb = kmalloc(sizeof(*fmsb), GFP_KERNEL);
@@ -991,7 +991,7 @@
ubi_free_vid_hdr(ubi, vh);
kfree(ech);
out:
- mutex_unlock(&ubi->fm_mutex);
+ up_write(&ubi->fm_protect);
if (ret == UBI_BAD_FASTMAP)
ubi_err(ubi, "Attach by fastmap failed, doing a full scan!");
return ret;
@@ -1340,24 +1340,24 @@
struct ubi_fastmap_layout *new_fm, *old_fm;
struct ubi_wl_entry *tmp_e;
- mutex_lock(&ubi->fm_mutex);
+ down_write(&ubi->fm_protect);
ubi_refill_pools(ubi);
if (ubi->ro_mode || ubi->fm_disabled) {
- mutex_unlock(&ubi->fm_mutex);
+ up_write(&ubi->fm_protect);
return 0;
}
ret = ubi_ensure_anchor_pebs(ubi);
if (ret) {
- mutex_unlock(&ubi->fm_mutex);
+ up_write(&ubi->fm_protect);
return ret;
}
new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
if (!new_fm) {
- mutex_unlock(&ubi->fm_mutex);
+ up_write(&ubi->fm_protect);
return -ENOMEM;
}
@@ -1447,16 +1447,16 @@
}
down_write(&ubi->work_sem);
- down_write(&ubi->fm_sem);
+ down_write(&ubi->fm_eba_sem);
ret = ubi_write_fastmap(ubi, new_fm);
- up_write(&ubi->fm_sem);
+ up_write(&ubi->fm_eba_sem);
up_write(&ubi->work_sem);
if (ret)
goto err;
out_unlock:
- mutex_unlock(&ubi->fm_mutex);
+ up_write(&ubi->fm_protect);
kfree(old_fm);
return ret;