tree 52d1ecd11d48faa7e6f8d6600c8e76807b0985a5
parent 09cc9fc7a7c3d872065426d7fb0f0ad6d3eb90fc
author Dave Chinner <dchinner@redhat.com> 1310098481 +1000
committer Al Viro <viro@zeniv.linux.org.uk> 1311140678 -0400

superblock: move pin_sb_for_writeback() to fs/super.c

The per-sb shrinker has the same requirement as the writeback
threads of ensuring that the superblock is usable and pinned for the
time it takes to run the work. Both need to take a passive reference
to the sb, take a read lock on the s_umount lock and then only
continue if an unmount is not in progress.

pin_sb_for_writeback() does this exactly, so move it to fs/super.c
and rename it to grab_super_passive() and exporting it via
fs/internal.h for all the VFS code to be able to use.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>