On Thu, 2007-05-10 at 18:38 -0400, J. Bruce Fields wrote:
> In 9d6a8c5c213e34c475e72b245a8eb709258e968c we changed posix_test_lock
> to modify its single file_lock argument instead of taking separate input
> and output arguments. This makes it no longer safe to set the output
> lock's fl_type to F_UNLCK before looking for a conflict, since that
> means searching for a conflict against a lock with type F_UNLCK.
>
> This fixes a regression which causes F_GETLK to incorrectly report no
> conflict on most filesystems (including any filesystem that doesn't do
> its own locking).
>
> Also fix posix_lock_to_flock() to copy the lock type. This isn't
> strictly necessary, since the caller already does this; but it seems
> less likely to cause confusion in the future.
>
> Thanks to Doug Chapman for the bug report.
>
> Signed-off-by: "J. Bruce Fields" <[email protected]>
> ---
> fs/locks.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 671a034..8ec16ab 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -669,7 +669,6 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> {
> struct file_lock *cfl;
>
> - fl->fl_type = F_UNLCK;
> lock_kernel();
> for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
> if (!IS_POSIX(cfl))
> @@ -681,7 +680,8 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> __locks_copy_lock(fl, cfl);
> unlock_kernel();
> return 1;
> - }
> + } else
> + fl->fl_type = F_UNLCK;
> unlock_kernel();
> return 0;
> }
> @@ -1632,6 +1632,7 @@ static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
> flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
> fl->fl_end - fl->fl_start + 1;
> flock->l_whence = 0;
> + flock->l_type = fl->fl_type;
> return 0;
> }
>
I tested this both with my little hacked up test program as well as with
the LTP tests. Looks good. Nice job on the quick turnaround on this
Bruce.
- Doug
-
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