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Eliminate a deadlock when creating snapshots. Blocking vn_start_write() must

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be called without any vnode locks held.  Remove calls to vn_start_write() and
vn_finished_write() in vnode_pager_putpages() and add these calls before the
vnode lock is obtained to most of the callers that don't already have them.
This commit is contained in:
tegge 2006-03-02 22:13:28 +00:00
parent 29fc266ddd
commit 774f51ad2c
6 changed files with 22 additions and 3 deletions
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2
sys/kern/vfs_subr.c
View File

@ -2801,6 +2801,7 @@ vfs_msync(struct mount *mp, int flags)
struct vnode *vp, *mvp;
struct vm_object *obj;
(void) vn_start_write(NULL, &mp, V_WAIT);
MNT_ILOCK(mp);
MNT_VNODE_FOREACH(vp, mp, mvp) {
VI_LOCK(vp);
@ -2831,6 +2832,7 @@ vfs_msync(struct mount *mp, int flags)
VI_UNLOCK(vp);
}
MNT_IUNLOCK(mp);
vn_finished_write(mp);
}
/*

3
sys/security/mac/mac_process.c
View File

@ -330,6 +330,7 @@ mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
vm_object_t backing_object, object;
vm_ooffset_t offset;
struct vnode *vp;
struct mount *mp;
if (!mac_mmap_revocation)
return;
@ -407,6 +408,7 @@ mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
* copy-on-write.
*/
vm_object_reference(object);
(void) vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
VM_OBJECT_LOCK(object);
vm_object_page_clean(object,
@ -416,6 +418,7 @@ mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
OBJPC_SYNC);
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0, td);
vn_finished_write(mp);
vm_object_deallocate(object);
/*
* Why bother if there's no read permissions

12
sys/ufs/ffs/ffs_rawread.c
View File

@ -101,6 +101,7 @@ ffs_rawread_sync(struct vnode *vp, struct thread *td)
int error;
int upgraded;
struct bufobj *bo;
struct mount *mp;
/* Check for dirty mmap, pending writes and dirty buffers */
spl = splbio();
@ -112,7 +113,15 @@ ffs_rawread_sync(struct vnode *vp, struct thread *td)
splx(spl);
VI_UNLOCK(vp);
if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE)
upgraded = 1;
else
upgraded = 0;
VOP_UNLOCK(vp, 0, td);
(void) vn_start_write(vp, &mp, V_WAIT);
VOP_LOCK(vp, LK_EXCLUSIVE, td);
} else if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
upgraded = 1;
/* Upgrade to exclusive lock, this might block */
VOP_LOCK(vp, LK_UPGRADE, td);
@ -161,6 +170,7 @@ ffs_rawread_sync(struct vnode *vp, struct thread *td)
VI_UNLOCK(vp);
if (upgraded != 0)
VOP_LOCK(vp, LK_DOWNGRADE, td);
vn_finished_write(mp);
} else {
splx(spl);
VI_UNLOCK(vp);

3
sys/vm/vm_contig.c
View File

@ -91,6 +91,7 @@ vm_contig_launder_page(vm_page_t m)
vm_object_t object;
vm_page_t m_tmp;
struct vnode *vp;
struct mount *mp;
object = m->object;
if (!VM_OBJECT_TRYLOCK(object))
@ -109,12 +110,14 @@ vm_contig_launder_page(vm_page_t m)
vp = object->handle;
vm_object_reference_locked(object);
VM_OBJECT_UNLOCK(object);
(void) vn_start_write(vp, &mp, V_WAIT);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
VM_OBJECT_LOCK(object);
vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0, curthread);
vm_object_deallocate(object);
vn_finished_write(mp);
vm_page_lock_queues();
return (0);
} else if (object->type == OBJT_SWAP ||

3
sys/vm/vm_object.c
View File

@ -993,6 +993,7 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
{
vm_object_t backing_object;
struct vnode *vp;
struct mount *mp;
int flags;
if (object == NULL)
@ -1023,6 +1024,7 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
int vfslocked;
vp = object->handle;
VM_OBJECT_UNLOCK(object);
(void) vn_start_write(vp, &mp, V_WAIT);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
flags = (syncio || invalidate) ? OBJPC_SYNC : 0;
@ -1035,6 +1037,7 @@ vm_object_sync(vm_object_t object, vm_ooffset_t offset, vm_size_t size,
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0, curthread);
VFS_UNLOCK_GIANT(vfslocked);
vn_finished_write(mp);
VM_OBJECT_LOCK(object);
}
if ((object->type == OBJT_VNODE ||

2
sys/vm/vnode_pager.c
View File

@ -1017,11 +1017,9 @@ vnode_pager_putpages(object, m, count, sync, rtvals)
VM_OBJECT_UNLOCK(object);
if (vp->v_type != VREG)
mp = NULL;
(void)vn_start_write(vp, &mp, V_WAIT);
rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
KASSERT(rtval != EOPNOTSUPP,
("vnode_pager: stale FS putpages\n"));
vn_finished_write(mp);
VM_OBJECT_LOCK(object);
}