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locks: fix F_GETLK regression (failure to find conflicts) 

In 9d6a8c5c21 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" <bfields@citi.umich.edu>
Acked-by: Doug Chapman <doug.chapman@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
J. Bruce Fields 2007-05-10 18:38:43 -04:00 committed by Linus Torvalds
parent a9deecba19
commit 129a84de23
1 changed files with 3 additions and 2 deletions
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5
fs/locks.c
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@ -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;
}