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mm: Handle MADV_WILLNEED through vfs_fadvise() 

Currently handling of MADV_WILLNEED hint calls directly into readahead
code. Handle it by calling vfs_fadvise() instead so that filesystem can
use its ->fadvise() callback to acquire necessary locks or otherwise
prepare for the request.

Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Boaz Harrosh <boazh@netapp.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
alistair/sunxi64-5.4-dsi
Jan Kara 2019-08-29 09:04:11 -07:00 committed by Darrick J. Wong
parent ddbca70cc4
commit 692fe62433
1 changed files with 16 additions and 6 deletions
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22
mm/madvise.c
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@ -14,6 +14,7 @@
#include <linux/userfaultfd_k.h>
#include <linux/hugetlb.h>
#include <linux/falloc.h>
#include <linux/fadvise.h>
#include <linux/sched.h>
#include <linux/ksm.h>
#include <linux/fs.h>
@ -275,6 +276,7 @@ static long madvise_willneed(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
struct file *file = vma->vm_file;
loff_t offset;
*prev = vma;
#ifdef CONFIG_SWAP
@ -298,12 +300,20 @@ static long madvise_willneed(struct vm_area_struct *vma,
return 0;
}
start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
if (end > vma->vm_end)
end = vma->vm_end;
end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
force_page_cache_readahead(file->f_mapping, file, start, end - start);
/*
* Filesystem's fadvise may need to take various locks. We need to
* explicitly grab a reference because the vma (and hence the
* vma's reference to the file) can go away as soon as we drop
* mmap_sem.
*/
*prev = NULL; /* tell sys_madvise we drop mmap_sem */
get_file(file);
up_read(&current->mm->mmap_sem);
offset = (loff_t)(start - vma->vm_start)
+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
fput(file);
down_read(&current->mm->mmap_sem);
return 0;
}