4 a.m.
On Mon 26-02-18 20:20:11, Dan Williams wrote:
dax_sem_{up,down}_write_sem() allow the ext2 dax semaphore to be
compiled
out in the CONFIG_FS_DAX=n case. However there are still some open coded
uses of the semaphore. Add dax_sem_{up_read,down_read,_is_locked}()
helpers and convert all open-coded usages of the semaphore to the
helpers.
Just one nit below. With that fixed you can add:
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Jan Kara <jack(a)suse.com>
Cc: <stable(a)vger.kernel.org>
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Signed-off-by: Dan Williams <dan.j.williams(a)intel.com>
---
fs/ext2/ext2.h | 6 ++++++
fs/ext2/file.c | 5 ++---
fs/ext2/inode.c | 4 +---
3 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 032295e1d386..7ceb29733cdb 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -711,9 +711,15 @@ struct ext2_inode_info {
#ifdef CONFIG_FS_DAX
#define dax_sem_down_write(ext2_inode) down_write(&(ext2_inode)->dax_sem)
#define dax_sem_up_write(ext2_inode) up_write(&(ext2_inode)->dax_sem)
+#define dax_sem_is_locked(ext2_inode) rwsem_is_locked(&(ext2_inode)->dax_sem)
+#define dax_sem_down_read(ext2_inode) down_read(&(ext2_inode)->dax_sem)
+#define dax_sem_up_read(ext2_inode) up_read(&(ext2_inode)->dax_sem)
#else
#define dax_sem_down_write(ext2_inode)
#define dax_sem_up_write(ext2_inode)
+#define dax_sem_is_locked(ext2_inode) (true)
This is a bit dangerous as depending on the use of dax_sem_is_locked()
you'd need this to return true or false. E.g. assume we'd have a place
where we'd like to do:
WARN_ON(dax_sem_is_locked(inode));
or just
if (dax_sem_is_locked(inode))
bail out due to congestion...
How I'd solve this is that I'd define:
#define assert_dax_sem_locked(ext2_inode)
WARN_ON(rwsem_is_locked(&(ext2_inode)->dax_sem)
and just as do {} while (0) for !CONFIG_FS_DAX.
Honza
--
Jan Kara <jack(a)suse.com>
SUSE Labs, CR