diff mbox series

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

Message ID 161340390150.1303470.509630287091953754.stgit@warthog.procyon.org.uk (mailing list archive)
State New
Headers show
Series Network fs helper library & fscache kiocb API [ver #3] | expand

Commit Message

David Howells Feb. 15, 2021, 3:45 p.m. UTC
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@redhat.com>
cc: Alexander Viro <viro@zeniv.linux.org.uk>
cc: Christoph Hellwig <hch@lst.de>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
---

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

Comments

Christoph Hellwig Feb. 16, 2021, 10:26 a.m. UTC | #1
On Mon, Feb 15, 2021 at 03:45:01PM +0000, David Howells wrote:
> 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().

I don't think this is the right thing to do.  Instead of calling
into ->read_iter / ->write_iter directly this should be using helpers.

What prevents you from using vfs_iocb_iter_read and
vfs_iocb_iter_write which seem the right level of abstraction for this?
David Howells Feb. 16, 2021, 11:55 a.m. UTC | #2
Christoph Hellwig <hch@lst.de> wrote:

> > 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().
> 
> I don't think this is the right thing to do.  Instead of calling
> into ->read_iter / ->write_iter directly this should be using helpers.
> 
> What prevents you from using vfs_iocb_iter_read and
> vfs_iocb_iter_write which seem the right level of abstraction for this?

I don't think they existed when I wrote this code.  Should aio use that too,
btw?  I modelled my code on aio_read() and aio_write().

But I can certainly switch to using vfs_iocb_iter_read/write, though the
trivial checks are redundant.  The fsnotify call, I guess I'm missing though
(and is that missing in aio_read/write() also?).

David
diff mbox series

Patch

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)
 {