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authorTrond Myklebust <Trond.Myklebust@netapp.com>2007-09-25 15:55:03 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-26 12:22:04 -0400
commit255129d1e9ca0ed3d69d5517fae3e03d7ab4b806 (patch)
treee3dedbffebd4f0e15da97684500296c9bc4d3d6a /fs/lockd/svclock.c
parentf6a592e8abd2f2394623ce5427cbb4c265495974 (diff)
NLM: Fix a circular lock dependency in lockd
The problem is that the garbage collector for the 'host' structures nlm_gc_hosts(), holds nlm_host_mutex while calling down to nlmsvc_mark_resources, which, eventually takes the file->f_mutex. We cannot therefore call nlmsvc_lookup_host() from within nlmsvc_create_block, since the caller will already hold file->f_mutex, so the attempt to grab nlm_host_mutex may deadlock. Fix the problem by calling nlmsvc_lookup_host() outside the file->f_mutex. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/lockd/svclock.c')
-rw-r--r--fs/lockd/svclock.c29
1 files changed, 18 insertions, 11 deletions
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index a21e4bc5444b..d098c7af0d22 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -171,19 +171,14 @@ found:
171 * GRANTED_RES message by cookie, without having to rely on the client's IP 171 * GRANTED_RES message by cookie, without having to rely on the client's IP
172 * address. --okir 172 * address. --okir
173 */ 173 */
174static inline struct nlm_block * 174static struct nlm_block *
175nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file, 175nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
176 struct nlm_lock *lock, struct nlm_cookie *cookie) 176 struct nlm_file *file, struct nlm_lock *lock,
177 struct nlm_cookie *cookie)
177{ 178{
178 struct nlm_block *block; 179 struct nlm_block *block;
179 struct nlm_host *host;
180 struct nlm_rqst *call = NULL; 180 struct nlm_rqst *call = NULL;
181 181
182 /* Create host handle for callback */
183 host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
184 if (host == NULL)
185 return NULL;
186
187 call = nlm_alloc_call(host); 182 call = nlm_alloc_call(host);
188 if (call == NULL) 183 if (call == NULL)
189 return NULL; 184 return NULL;
@@ -366,6 +361,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
366 struct nlm_lock *lock, int wait, struct nlm_cookie *cookie) 361 struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
367{ 362{
368 struct nlm_block *block = NULL; 363 struct nlm_block *block = NULL;
364 struct nlm_host *host;
369 int error; 365 int error;
370 __be32 ret; 366 __be32 ret;
371 367
@@ -377,6 +373,10 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
377 (long long)lock->fl.fl_end, 373 (long long)lock->fl.fl_end,
378 wait); 374 wait);
379 375
376 /* Create host handle for callback */
377 host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
378 if (host == NULL)
379 return nlm_lck_denied_nolocks;
380 380
381 /* Lock file against concurrent access */ 381 /* Lock file against concurrent access */
382 mutex_lock(&file->f_mutex); 382 mutex_lock(&file->f_mutex);
@@ -385,7 +385,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
385 */ 385 */
386 block = nlmsvc_lookup_block(file, lock); 386 block = nlmsvc_lookup_block(file, lock);
387 if (block == NULL) { 387 if (block == NULL) {
388 block = nlmsvc_create_block(rqstp, file, lock, cookie); 388 block = nlmsvc_create_block(rqstp, nlm_get_host(host), file,
389 lock, cookie);
389 ret = nlm_lck_denied_nolocks; 390 ret = nlm_lck_denied_nolocks;
390 if (block == NULL) 391 if (block == NULL)
391 goto out; 392 goto out;
@@ -449,6 +450,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
449out: 450out:
450 mutex_unlock(&file->f_mutex); 451 mutex_unlock(&file->f_mutex);
451 nlmsvc_release_block(block); 452 nlmsvc_release_block(block);
453 nlm_release_host(host);
452 dprintk("lockd: nlmsvc_lock returned %u\n", ret); 454 dprintk("lockd: nlmsvc_lock returned %u\n", ret);
453 return ret; 455 return ret;
454} 456}
@@ -477,10 +479,15 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
477 479
478 if (block == NULL) { 480 if (block == NULL) {
479 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL); 481 struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
482 struct nlm_host *host;
480 483
481 if (conf == NULL) 484 if (conf == NULL)
482 return nlm_granted; 485 return nlm_granted;
483 block = nlmsvc_create_block(rqstp, file, lock, cookie); 486 /* Create host handle for callback */
487 host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
488 if (host == NULL)
489 return nlm_lck_denied_nolocks;
490 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
484 if (block == NULL) { 491 if (block == NULL) {
485 kfree(conf); 492 kfree(conf);
486 return nlm_granted; 493 return nlm_granted;