diff options
| author | Kiyoshi Ueda <k-ueda@ct.jp.nec.com> | 2010-08-12 04:13:55 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-26 16:43:37 -0700 |
| commit | fbc69b9c7dae031359253e8c2ba31ea9c72172a2 (patch) | |
| tree | 56a4d6e80eb1287bae687074b3885db2089b42ea | |
| parent | 97159b7360b1e15419b417da17e7cd227a4195cc (diff) | |
dm ioctl: release _hash_lock between devices in remove_all
commit 98f332855effef02aeb738e4d62e9a5b903c52fd upstream.
This patch changes dm_hash_remove_all() to release _hash_lock when
removing a device. After removing the device, dm_hash_remove_all()
takes _hash_lock and searches the hash from scratch again.
This patch is a preparation for the next patch, which changes device
deletion code to wait for md reference to be 0. Without this patch,
the wait in the next patch may cause AB-BA deadlock:
CPU0 CPU1
-----------------------------------------------------------------------
dm_hash_remove_all()
down_write(_hash_lock)
table_status()
md = find_device()
dm_get(md)
<increment md->holders>
dm_get_live_or_inactive_table()
dm_get_inactive_table()
down_write(_hash_lock)
<in the md deletion code>
<wait for md->holders to be 0>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/md/dm-ioctl.c | 44 |
1 files changed, 25 insertions, 19 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index d7500e1c26f..f81c5360414 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -249,40 +249,46 @@ static void __hash_remove(struct hash_cell *hc) static void dm_hash_remove_all(int keep_open_devices) { - int i, dev_skipped, dev_removed; + int i, dev_skipped; struct hash_cell *hc; - struct list_head *tmp, *n; + struct mapped_device *md; + +retry: + dev_skipped = 0; down_write(&_hash_lock); -retry: - dev_skipped = dev_removed = 0; for (i = 0; i < NUM_BUCKETS; i++) { - list_for_each_safe (tmp, n, _name_buckets + i) { - hc = list_entry(tmp, struct hash_cell, name_list); + list_for_each_entry(hc, _name_buckets + i, name_list) { + md = hc->md; + dm_get(md); - if (keep_open_devices && - dm_lock_for_deletion(hc->md)) { + if (keep_open_devices && dm_lock_for_deletion(md)) { + dm_put(md); dev_skipped++; continue; } + __hash_remove(hc); - dev_removed = 1; - } - } - /* - * Some mapped devices may be using other mapped devices, so if any - * still exist, repeat until we make no further progress. - */ - if (dev_skipped) { - if (dev_removed) - goto retry; + up_write(&_hash_lock); - DMWARN("remove_all left %d open device(s)", dev_skipped); + dm_put(md); + + /* + * Some mapped devices may be using other mapped + * devices, so repeat until we make no further + * progress. If a new mapped device is created + * here it will also get removed. + */ + goto retry; + } } up_write(&_hash_lock); + + if (dev_skipped) + DMWARN("remove_all left %d open device(s)", dev_skipped); } static int dm_hash_rename(uint32_t cookie, uint32_t *flags, const char *old, |