mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE

Now tmpfs supports hole-punching via fallocate(), switch madvise_remove()
to use do_fallocate() instead of vmtruncate_range(): which extends
madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs.

There is one more user of vmtruncate_range() in our tree,
staging/android's ashmem_shrink(): convert it to use do_fallocate() too
(but if its unpinned areas are already unmapped - I don't know - then it
would do better to use shmem_truncate_range() directly).

Based-on-patch-by: Cong Wang <amwang@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Colin Cross <ccross@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger@dilger.ca>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ben Myers <bpm@sgi.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 4511420849bc..e84dbecd0991 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/file.h>
 #include <linux/fs.h>
+#include <linux/falloc.h>
 #include <linux/miscdevice.h>
 #include <linux/security.h>
 #include <linux/mm.h>
@@ -363,11 +364,12 @@ static int ashmem_shrink(struct shrinker *s, struct shrink_control *sc)
 
         mutex_lock(&ashmem_mutex);
         list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
-                struct inode *inode = range->asma->file->f_dentry->d_inode;
                 loff_t start = range->pgstart * PAGE_SIZE;
-                loff_t end = (range->pgend + 1) * PAGE_SIZE - 1;
+                loff_t end = (range->pgend + 1) * PAGE_SIZE;
 
-                vmtruncate_range(inode, start, end);
+                do_fallocate(range->asma->file,
+                                FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+                                start, end - start);
                 range->purged = ASHMEM_WAS_PURGED;
                 lru_del(range);