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authorJan Kara <jack@suse.cz>2019-08-29 09:04:11 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-08-30 22:43:58 -0700
commit692fe62433d4ca47605b39f7c416efd6679ba694 (patch)
tree33d124b7b007e911141c7a3d527a4dc670eb7b4c
parentddbca70cc45c0ac97ff6d9529e45f10b8ae73ad4 (diff)
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>
-rw-r--r--mm/madvise.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
index 968df3aa069f..bac973b9f2cc 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -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;
}