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ceph: preallocate flock state without locks held

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When the lock_kernel() turns into lock_flocks() and a spinlock, we won't
be able to do allocations with the lock held.  Preallocate space without
the lock, and retry if the lock state changes out from underneath us.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Greg Farnum 2010-09-17 10:24:02 -07:00 committed by Sage Weil
parent ac0b74d8a1
commit fca4451acf
2 changed files with 42 additions and 13 deletions
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17
fs/ceph/locks.c
View file

@ -181,8 +181,9 @@ void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
* Encode the flock and fcntl locks for the given inode into the pagelist.
* Format is: #fcntl locks, sequential fcntl locks, #flock locks,
* sequential flock locks.
* Must be called with BLK already held, and the lock numbers should have
* been gathered under the same lock holding window.
* Must be called with lock_flocks() already held.
* If we encounter more of a specific lock type than expected,
* we return the value 1.
*/
int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
int num_fcntl_locks, int num_flock_locks)
@ -190,6 +191,8 @@ int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
struct file_lock *lock;
struct ceph_filelock cephlock;
int err = 0;
int seen_fcntl = 0;
int seen_flock = 0;
dout("encoding %d flock and %d fcntl locks", num_flock_locks,
num_fcntl_locks);
@ -198,6 +201,11 @@ int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
goto fail;
for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
if (lock->fl_flags & FL_POSIX) {
++seen_fcntl;
if (seen_fcntl > num_fcntl_locks) {
err = -ENOSPC;
goto fail;
}
err = lock_to_ceph_filelock(lock, &cephlock);
if (err)
goto fail;
@ -213,6 +221,11 @@ int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
goto fail;
for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
if (lock->fl_flags & FL_FLOCK) {
++seen_flock;
if (seen_flock > num_flock_locks) {
err = -ENOSPC;
goto fail;
}
err = lock_to_ceph_filelock(lock, &cephlock);
if (err)
goto fail;

38
fs/ceph/mds_client.c
View file

@ -2365,19 +2365,35 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
if (recon_state->flock) {
int num_fcntl_locks, num_flock_locks;
struct ceph_pagelist_cursor trunc_point;
lock_kernel();
ceph_count_locks(inode, &num_fcntl_locks, &num_flock_locks);
rec.v2.flock_len = (2*sizeof(u32) +
(num_fcntl_locks+num_flock_locks) *
sizeof(struct ceph_filelock));
ceph_pagelist_set_cursor(pagelist, &trunc_point);
do {
lock_kernel();
ceph_count_locks(inode, &num_fcntl_locks,
&num_flock_locks);
rec.v2.flock_len = (2*sizeof(u32) +
(num_fcntl_locks+num_flock_locks) *
sizeof(struct ceph_filelock));
unlock_kernel();
err = ceph_pagelist_append(pagelist, &rec, reclen);
if (!err)
err = ceph_encode_locks(inode, pagelist,
num_fcntl_locks,
num_flock_locks);
unlock_kernel();
/* pre-alloc pagelist */
ceph_pagelist_truncate(pagelist, &trunc_point);
err = ceph_pagelist_append(pagelist, &rec, reclen);
if (!err)
err = ceph_pagelist_reserve(pagelist,
rec.v2.flock_len);
/* encode locks */
if (!err) {
lock_kernel();
err = ceph_encode_locks(inode,
pagelist,
num_fcntl_locks,
num_flock_locks);
unlock_kernel();
}
} while (err == -ENOSPC);
} else {
err = ceph_pagelist_append(pagelist, &rec, reclen);
}