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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-16 08:58:47 -0600
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-16 08:58:47 -0600
commit53b95d6341c142a02538e41bdf1405ef8888bf8b (patch)
treef87d6f57029b6c101c9909cd143de34196c63b1f
parentda06df548e2b82848bcc32342234d0f04340a41c (diff)
parent2ece173e4715031c031de9114491eee80a69cf68 (diff)
downloadlinux-53b95d6341c142a02538e41bdf1405ef8888bf8b.tar.gz
Merge tag 'locks-v3.17-2' of git://git.samba.org/jlayton/linux
Pull file locking bugfixes from Jeff Layton: "Most of these patches are to fix a long-standing regression that crept in when the BKL was removed from the file-locking code. The code was converted to use a conventional spinlock, but some fl_release_private ops can block and you can end up sleeping inside the lock. There's also a patch to make /proc/locks show delegations as 'DELEG'" * tag 'locks-v3.17-2' of git://git.samba.org/jlayton/linux: locks: update Locking documentation to clarify fl_release_private behavior locks: move locks_free_lock calls in do_fcntl_add_lease outside spinlock locks: defer freeing locks in locks_delete_lock until after i_lock has been dropped locks: don't reuse file_lock in __posix_lock_file locks: don't call locks_release_private from locks_copy_lock locks: show delegations as "DELEG" in /proc/locks
-rw-r--r--Documentation/filesystems/Locking6
-rw-r--r--fs/locks.c86
2 files changed, 62 insertions, 30 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index b18dd1779029..f1997e9da61f 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -349,7 +349,11 @@ prototypes:
locking rules:
inode->i_lock may block
fl_copy_lock: yes no
-fl_release_private: maybe no
+fl_release_private: maybe maybe[1]
+
+[1]: ->fl_release_private for flock or POSIX locks is currently allowed
+to block. Leases however can still be freed while the i_lock is held and
+so fl_release_private called on a lease should not block.
----------------------- lock_manager_operations ---------------------------
prototypes:
diff --git a/fs/locks.c b/fs/locks.c
index a6f54802d277..cb66fb05ad4a 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -247,6 +247,18 @@ void locks_free_lock(struct file_lock *fl)
}
EXPORT_SYMBOL(locks_free_lock);
+static void
+locks_dispose_list(struct list_head *dispose)
+{
+ struct file_lock *fl;
+
+ while (!list_empty(dispose)) {
+ fl = list_first_entry(dispose, struct file_lock, fl_block);
+ list_del_init(&fl->fl_block);
+ locks_free_lock(fl);
+ }
+}
+
void locks_init_lock(struct file_lock *fl)
{
memset(fl, 0, sizeof(struct file_lock));
@@ -285,7 +297,8 @@ EXPORT_SYMBOL(__locks_copy_lock);
void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
- locks_release_private(new);
+ /* "new" must be a freshly-initialized lock */
+ WARN_ON_ONCE(new->fl_ops);
__locks_copy_lock(new, fl);
new->fl_file = fl->fl_file;
@@ -650,12 +663,16 @@ static void locks_unlink_lock(struct file_lock **thisfl_p)
*
* Must be called with i_lock held!
*/
-static void locks_delete_lock(struct file_lock **thisfl_p)
+static void locks_delete_lock(struct file_lock **thisfl_p,
+ struct list_head *dispose)
{
struct file_lock *fl = *thisfl_p;
locks_unlink_lock(thisfl_p);
- locks_free_lock(fl);
+ if (dispose)
+ list_add(&fl->fl_block, dispose);
+ else
+ locks_free_lock(fl);
}
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
@@ -811,6 +828,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
struct inode * inode = file_inode(filp);
int error = 0;
int found = 0;
+ LIST_HEAD(dispose);
if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
new_fl = locks_alloc_lock();
@@ -833,7 +851,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
if (request->fl_type == fl->fl_type)
goto out;
found = 1;
- locks_delete_lock(before);
+ locks_delete_lock(before, &dispose);
break;
}
@@ -880,6 +898,7 @@ out:
spin_unlock(&inode->i_lock);
if (new_fl)
locks_free_lock(new_fl);
+ locks_dispose_list(&dispose);
return error;
}
@@ -893,6 +912,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
struct file_lock **before;
int error;
bool added = false;
+ LIST_HEAD(dispose);
/*
* We may need two file_lock structures for this operation,
@@ -988,7 +1008,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
else
request->fl_end = fl->fl_end;
if (added) {
- locks_delete_lock(before);
+ locks_delete_lock(before, &dispose);
continue;
}
request = fl;
@@ -1018,21 +1038,24 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
* one (This may happen several times).
*/
if (added) {
- locks_delete_lock(before);
+ locks_delete_lock(before, &dispose);
continue;
}
- /* Replace the old lock with the new one.
- * Wake up anybody waiting for the old one,
- * as the change in lock type might satisfy
- * their needs.
+ /*
+ * Replace the old lock with new_fl, and
+ * remove the old one. It's safe to do the
+ * insert here since we know that we won't be
+ * using new_fl later, and that the lock is
+ * just replacing an existing lock.
*/
- locks_wake_up_blocks(fl);
- fl->fl_start = request->fl_start;
- fl->fl_end = request->fl_end;
- fl->fl_type = request->fl_type;
- locks_release_private(fl);
- locks_copy_private(fl, request);
- request = fl;
+ error = -ENOLCK;
+ if (!new_fl)
+ goto out;
+ locks_copy_lock(new_fl, request);
+ request = new_fl;
+ new_fl = NULL;
+ locks_delete_lock(before, &dispose);
+ locks_insert_lock(before, request);
added = true;
}
}
@@ -1093,6 +1116,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
locks_free_lock(new_fl);
if (new_fl2)
locks_free_lock(new_fl2);
+ locks_dispose_list(&dispose);
return error;
}
@@ -1268,7 +1292,7 @@ int lease_modify(struct file_lock **before, int arg)
printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
fl->fl_fasync = NULL;
}
- locks_delete_lock(before);
+ locks_delete_lock(before, NULL);
}
return 0;
}
@@ -1737,13 +1761,10 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
ret = fl;
spin_lock(&inode->i_lock);
error = __vfs_setlease(filp, arg, &ret);
- if (error) {
- spin_unlock(&inode->i_lock);
- locks_free_lock(fl);
- goto out_free_fasync;
- }
- if (ret != fl)
- locks_free_lock(fl);
+ if (error)
+ goto out_unlock;
+ if (ret == fl)
+ fl = NULL;
/*
* fasync_insert_entry() returns the old entry if any.
@@ -1755,9 +1776,10 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
new = NULL;
error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
+out_unlock:
spin_unlock(&inode->i_lock);
-
-out_free_fasync:
+ if (fl)
+ locks_free_lock(fl);
if (new)
fasync_free(new);
return error;
@@ -2320,6 +2342,7 @@ void locks_remove_file(struct file *filp)
struct inode * inode = file_inode(filp);
struct file_lock *fl;
struct file_lock **before;
+ LIST_HEAD(dispose);
if (!inode->i_flock)
return;
@@ -2365,12 +2388,13 @@ void locks_remove_file(struct file *filp)
fl->fl_type, fl->fl_flags,
fl->fl_start, fl->fl_end);
- locks_delete_lock(before);
+ locks_delete_lock(before, &dispose);
continue;
}
before = &fl->fl_next;
}
spin_unlock(&inode->i_lock);
+ locks_dispose_list(&dispose);
}
/**
@@ -2452,7 +2476,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
seq_puts(f, "FLOCK ADVISORY ");
}
} else if (IS_LEASE(fl)) {
- seq_puts(f, "LEASE ");
+ if (fl->fl_flags & FL_DELEG)
+ seq_puts(f, "DELEG ");
+ else
+ seq_puts(f, "LEASE ");
+
if (lease_breaking(fl))
seq_puts(f, "BREAKING ");
else if (fl->fl_file)