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locks: defer freeing locks in locks_delete_lock until after i_lock has been dropped
In commit 72f98e7255
(locks: turn lock_flocks into a spinlock), we
moved from using the BKL to a global spinlock. With this change, we lost
the ability to block in the fl_release_private operation.
This is problematic for NFS (and probably some other filesystems as
well). Add a new list_head argument to locks_delete_lock. If that
argument is non-NULL, then queue any locks that we want to free to the
list instead of freeing them.
Then, add a new locks_dispose_list function that will walk such a list
and call locks_free_lock on them after the i_lock has been dropped.
Finally, change all of the callers of locks_delete_lock to pass in a
list_head, except for lease_modify. That function can be called long
after the i_lock has been acquired. Deferring the freeing of a lease
after unlocking it in that function is non-trivial until we overhaul
some of the spinlocking in the lease code.
Currently though, no filesystem that sets fl_release_private supports
leases, so this is not currently a problem. We'll eventually want to
make the same change in the lease code, but it needs a lot more work
before we can reasonably do so.
Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
This commit is contained in:
parent
b84d49f944
commit
ed9814d858
1 changed files with 30 additions and 8 deletions
38
fs/locks.c
38
fs/locks.c
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@ -247,6 +247,18 @@ void locks_free_lock(struct file_lock *fl)
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}
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EXPORT_SYMBOL(locks_free_lock);
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static void
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locks_dispose_list(struct list_head *dispose)
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{
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struct file_lock *fl;
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while (!list_empty(dispose)) {
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fl = list_first_entry(dispose, struct file_lock, fl_block);
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list_del_init(&fl->fl_block);
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locks_free_lock(fl);
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}
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}
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void locks_init_lock(struct file_lock *fl)
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{
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memset(fl, 0, sizeof(struct file_lock));
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@ -651,12 +663,16 @@ static void locks_unlink_lock(struct file_lock **thisfl_p)
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*
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* Must be called with i_lock held!
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*/
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static void locks_delete_lock(struct file_lock **thisfl_p)
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static void locks_delete_lock(struct file_lock **thisfl_p,
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struct list_head *dispose)
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{
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struct file_lock *fl = *thisfl_p;
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locks_unlink_lock(thisfl_p);
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locks_free_lock(fl);
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if (dispose)
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list_add(&fl->fl_block, dispose);
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else
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locks_free_lock(fl);
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}
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/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
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@ -812,6 +828,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
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struct inode * inode = file_inode(filp);
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int error = 0;
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int found = 0;
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LIST_HEAD(dispose);
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if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
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new_fl = locks_alloc_lock();
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@ -834,7 +851,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
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if (request->fl_type == fl->fl_type)
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goto out;
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found = 1;
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locks_delete_lock(before);
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locks_delete_lock(before, &dispose);
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break;
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}
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@ -881,6 +898,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
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spin_unlock(&inode->i_lock);
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if (new_fl)
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locks_free_lock(new_fl);
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locks_dispose_list(&dispose);
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return error;
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}
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@ -894,6 +912,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
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struct file_lock **before;
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int error;
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bool added = false;
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LIST_HEAD(dispose);
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/*
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* We may need two file_lock structures for this operation,
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@ -989,7 +1008,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
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else
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request->fl_end = fl->fl_end;
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if (added) {
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locks_delete_lock(before);
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locks_delete_lock(before, &dispose);
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continue;
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}
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request = fl;
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@ -1019,7 +1038,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
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* one (This may happen several times).
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*/
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if (added) {
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locks_delete_lock(before);
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locks_delete_lock(before, &dispose);
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continue;
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}
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/*
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@ -1035,7 +1054,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
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locks_copy_lock(new_fl, request);
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request = new_fl;
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new_fl = NULL;
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locks_delete_lock(before);
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locks_delete_lock(before, &dispose);
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locks_insert_lock(before, request);
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added = true;
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}
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@ -1097,6 +1116,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
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locks_free_lock(new_fl);
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if (new_fl2)
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locks_free_lock(new_fl2);
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locks_dispose_list(&dispose);
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return error;
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}
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@ -1272,7 +1292,7 @@ int lease_modify(struct file_lock **before, int arg)
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printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
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fl->fl_fasync = NULL;
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}
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locks_delete_lock(before);
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locks_delete_lock(before, NULL);
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}
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return 0;
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}
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@ -2324,6 +2344,7 @@ void locks_remove_file(struct file *filp)
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struct inode * inode = file_inode(filp);
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struct file_lock *fl;
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struct file_lock **before;
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LIST_HEAD(dispose);
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if (!inode->i_flock)
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return;
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@ -2369,12 +2390,13 @@ void locks_remove_file(struct file *filp)
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fl->fl_type, fl->fl_flags,
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fl->fl_start, fl->fl_end);
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locks_delete_lock(before);
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locks_delete_lock(before, &dispose);
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continue;
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}
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before = &fl->fl_next;
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}
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spin_unlock(&inode->i_lock);
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locks_dispose_list(&dispose);
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}
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/**
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