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locks: comment cleanups and clarifications

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Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Jeff Layton 2013-06-21 08:58:12 -04:00 committed by Al Viro
parent d4f22d19df
commit 1cb3601259
2 changed files with 31 additions and 8 deletions
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21
fs/locks.c
View file

@ -518,9 +518,10 @@ static void locks_insert_block(struct file_lock *blocker,
list_add(&waiter->fl_link, &blocked_list);
}
/* Wake up processes blocked waiting for blocker.
* If told to wait then schedule the processes until the block list
* is empty, otherwise empty the block list ourselves.
/*
* Wake up processes blocked waiting for blocker.
*
* Must be called with the file_lock_lock held!
*/
static void locks_wake_up_blocks(struct file_lock *blocker)
{
@ -806,6 +807,11 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
}
lock_flocks();
/*
* New lock request. Walk all POSIX locks and look for conflicts. If
* there are any, either return error or put the request on the
* blocker's list of waiters and the global blocked_list.
*/
if (request->fl_type != F_UNLCK) {
for_each_lock(inode, before) {
fl = *before;
@ -844,7 +850,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
before = &fl->fl_next;
}
/* Process locks with this owner. */
/* Process locks with this owner. */
while ((fl = *before) && posix_same_owner(request, fl)) {
/* Detect adjacent or overlapping regions (if same lock type)
*/
@ -930,10 +936,9 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
}
/*
* The above code only modifies existing locks in case of
* merging or replacing. If new lock(s) need to be inserted
* all modifications are done bellow this, so it's safe yet to
* bail out.
* The above code only modifies existing locks in case of merging or
* replacing. If new lock(s) need to be inserted all modifications are
* done below this, so it's safe yet to bail out.
*/
error = -ENOLCK; /* "no luck" */
if (right && left == right && !new_fl2)

18
include/linux/fs.h
View file

@ -926,6 +926,24 @@ int locks_in_grace(struct net *);
/* that will die - we need it for nfs_lock_info */
#include <linux/nfs_fs_i.h>
/*
* struct file_lock represents a generic "file lock". It's used to represent
* POSIX byte range locks, BSD (flock) locks, and leases. It's important to
* note that the same struct is used to represent both a request for a lock and
* the lock itself, but the same object is never used for both.
*
* FIXME: should we create a separate "struct lock_request" to help distinguish
* these two uses?
*
* The i_flock list is ordered by:
*
* 1) lock type -- FL_LEASEs first, then FL_FLOCK, and finally FL_POSIX
* 2) lock owner
* 3) lock range start
* 4) lock range end
*
* Obviously, the last two criteria only matter for POSIX locks.
*/
struct file_lock {
struct file_lock *fl_next; /* singly linked list for this inode */
struct list_head fl_link; /* doubly linked list of all locks */