NTFS: Fix a mount time deadlock.

Big thanks go to Mathias Kolehmainen for reporting the bug, providing
debug output and testing the patches I sent him to get it working.

The fix was to stop calling ntfs_attr_set() at mount time as that causes
balance_dirty_pages_ratelimited() to be called which on systems with
little memory actually tries to go and balance the dirty pages which tries
to take the s_umount semaphore but because we are still in fill_super()
across which the VFS holds s_umount for writing this results in a
deadlock.

We now do the dirty work by hand by submitting individual buffers.  This
has the annoying "feature" that mounting can take a few seconds if the
journal is large as we have clear it all.  One day someone should improve
on this by deferring the journal clearing to a helper kernel thread so it
can be done in the background but I don't have time for this at the moment
and the current solution works fine so I am leaving it like this for now.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 3 deletions

diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index b532a730cec2..e9da092e2772 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -34,7 +34,6 @@
 #include "dir.h"
 #include "debug.h"
 #include "inode.h"
-#include "attrib.h"
 #include "lcnalloc.h"
 #include "malloc.h"
 #include "mft.h"
@@ -2500,8 +2499,6 @@ retry_truncate:
         /* Resize the attribute record to best fit the new attribute size. */
         if (new_size < vol->mft_record_size &&
                         !ntfs_resident_attr_value_resize(m, a, new_size)) {
-                unsigned long flags;
-
                 /* The resize succeeded! */
                 flush_dcache_mft_record_page(ctx->ntfs_ino);
                 mark_mft_record_dirty(ctx->ntfs_ino);