[PATCH 04/33] vfs: Export rw_verify_area() for use by cachefiles

From: David Howells
Date: Mon Feb 15 2021 - 11:57:48 EST


Export rw_verify_area() for so that cachefiles can use it before issuing
call_read_iter() and call_write_iter() to effect async DIO operations
against the cache. This is analogous to aio_read() and aio_write().

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
cc: Christoph Hellwig <hch@xxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: linux-mm@xxxxxxxxx
cc: linux-cachefs@xxxxxxxxxx
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
cc: linux-nfs@xxxxxxxxxxxxxxx
cc: linux-cifs@xxxxxxxxxxxxxxx
cc: ceph-devel@xxxxxxxxxxxxxxx
cc: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
---

fs/internal.h | 5 -----
fs/read_write.c | 1 +
include/linux/fs.h | 1 +
3 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 77c50befbfbe..92e686249c40 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -164,11 +164,6 @@ extern char *simple_dname(struct dentry *, char *, int);
extern void dput_to_list(struct dentry *, struct list_head *);
extern void shrink_dentry_list(struct list_head *);

-/*
- * read_write.c
- */
-extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
-
/*
* pipe.c
*/
diff --git a/fs/read_write.c b/fs/read_write.c
index 75f764b43418..fe84e11245bd 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -400,6 +400,7 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
return security_file_permission(file,
read_write == READ ? MAY_READ : MAY_WRITE);
}
+EXPORT_SYMBOL(rw_verify_area);

static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd47deea7c17..493804856ab3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2760,6 +2760,7 @@ extern int notify_change(struct dentry *, struct iattr *, struct inode **);
extern int inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);
extern int __check_sticky(struct inode *dir, struct inode *inode);
+extern int rw_verify_area(int, struct file *, const loff_t *, size_t);

static inline bool execute_ok(struct inode *inode)
{