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Commit 3f31d075 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

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: default avatarCong Wang <amwang@redhat.com>
Signed-off-by: default avatarHugh 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 83e4fa9c

drivers/staging/android/ashmem.c

+5 −3
Original line number Diff line number Diff line
@@ -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);

mm/madvise.c

+7 −8
Original line number Diff line number Diff line
@@ -11,8 +11,10 @@ 
#include <linux/mempolicy.h>

#include <linux/page-isolation.h>

#include <linux/hugetlb.h>

#include <linux/falloc.h>

#include <linux/sched.h>

#include <linux/ksm.h>

#include <linux/fs.h>



/*

 * Any behaviour which results in changes to the vma->vm_flags needs to
@@ -200,8 +202,7 @@ static long madvise_remove(struct vm_area_struct *vma, 
				struct vm_area_struct **prev,

				unsigned long start, unsigned long end)

{

	struct address_space *mapping;

	loff_t offset, endoff;

	loff_t offset;

	int error;



	*prev = NULL;	/* tell sys_madvise we drop mmap_sem */
@@ -217,16 +218,14 @@ static long madvise_remove(struct vm_area_struct *vma, 
	if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))

		return -EACCES;



	mapping = vma->vm_file->f_mapping;



	offset = (loff_t)(start - vma->vm_start)

			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);

	endoff = (loff_t)(end - vma->vm_start - 1)

			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);



	/* vmtruncate_range needs to take i_mutex */

	/* filesystem's fallocate may need to take i_mutex */

	up_read(&current->mm->mmap_sem);

	error = vmtruncate_range(mapping->host, offset, endoff);

	error = do_fallocate(vma->vm_file,

				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,

				offset, end - start);

	down_read(&current->mm->mmap_sem);

	return error;

}