diff options
| -rw-r--r-- | fs/locks.c | 21 | ||||
| -rw-r--r-- | include/linux/fs.h | 18 |
2 files changed, 31 insertions, 8 deletions
diff --git a/fs/locks.c b/fs/locks.c index 804bb9e01a6..ddeab49fe2b 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -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) diff --git a/include/linux/fs.h b/include/linux/fs.h index 6cfc9a29a78..ed9fdaaf322 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -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 */ |