Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 2/3] kill-the-BKL/reiserfs: lock only once in reiserfs_truncate_file | Date | Tue, 14 Apr 2009 05:34:24 +0200 |
| |
Impact: fix a deadlock
reiserfs_truncate_file() can be called from multiple context where the write lock can be already hold or not.
This function also acquire (possibly recursively) the write lock. Subsequent releases before sleeping will not actually release the lock because we may be in more than one lock depth degree.
A typical case is:
reiserfs_file_release { acquire_the_lock() reiserfs_truncate_file() reacquire_the_lock() journal_begin() { do_journal_begin_r() { reiserfs_wait_on_write_block() { /* * Not released because still one * depth owned */ release_lock() wait_for_event()
At this stage the event never happen because the one which provides it needs the write lock.
We use reiserfs_write_lock_once() here to ensure that we don't acquire the write lock recursively.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- fs/reiserfs/inode.c | 10 +++++++--- 1 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c index 88ef0b7..153668e 100644 --- a/fs/reiserfs/inode.c +++ b/fs/reiserfs/inode.c @@ -2083,8 +2083,9 @@ int reiserfs_truncate_file(struct inode *inode, int update_timestamps) int error; struct buffer_head *bh = NULL; int err2; + int lock_depth; - reiserfs_write_lock(inode->i_sb); + lock_depth = reiserfs_write_lock_once(inode->i_sb); if (inode->i_size > 0) { error = grab_tail_page(inode, &page, &bh); @@ -2153,14 +2154,17 @@ int reiserfs_truncate_file(struct inode *inode, int update_timestamps) page_cache_release(page); } - reiserfs_write_unlock(inode->i_sb); + reiserfs_write_unlock_once(inode->i_sb, lock_depth); + return 0; out: if (page) { unlock_page(page); page_cache_release(page); } - reiserfs_write_unlock(inode->i_sb); + + reiserfs_write_unlock_once(inode->i_sb, lock_depth); + return error; } -- 1.6.1
| |