Patch "orangefs: fix deadlock; do not write i_size in read_iter" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    orangefs: fix deadlock; do not write i_size in read_iter

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     orangefs-fix-deadlock-do-not-write-i_size-in-read_iter.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6793f1c450b1533a5e9c2493490de771d38b24f9 Mon Sep 17 00:00:00 2001
From: Martin Brandenburg <martin@omnibond.com>
Date: Thu, 25 Jan 2018 19:39:44 -0500
Subject: orangefs: fix deadlock; do not write i_size in read_iter

From: Martin Brandenburg <martin@omnibond.com>

commit 6793f1c450b1533a5e9c2493490de771d38b24f9 upstream.

After do_readv_writev, the inode cache is invalidated anyway, so i_size
will never be read.  It will be fetched from the server which will also
know about updates from other machines.

Fixes deadlock on 32-bit SMP.

See https://marc.info/?l=linux-fsdevel&m=151268557427760&w=2

Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/orangefs/file.c            |    7 ++-----
 fs/orangefs/orangefs-kernel.h |   11 -----------
 2 files changed, 2 insertions(+), 16 deletions(-)

--- a/fs/orangefs/file.c
+++ b/fs/orangefs/file.c
@@ -446,7 +446,7 @@ ssize_t orangefs_inode_read(struct inode
 static ssize_t orangefs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct file *file = iocb->ki_filp;
-	loff_t pos = *(&iocb->ki_pos);
+	loff_t pos = iocb->ki_pos;
 	ssize_t rc = 0;
 
 	BUG_ON(iocb->private);
@@ -485,9 +485,6 @@ static ssize_t orangefs_file_write_iter(
 		}
 	}
 
-	if (file->f_pos > i_size_read(file->f_mapping->host))
-		orangefs_i_size_write(file->f_mapping->host, file->f_pos);
-
 	rc = generic_write_checks(iocb, iter);
 
 	if (rc <= 0) {
@@ -501,7 +498,7 @@ static ssize_t orangefs_file_write_iter(
 	 * pos to the end of the file, so we will wait till now to set
 	 * pos...
 	 */
-	pos = *(&iocb->ki_pos);
+	pos = iocb->ki_pos;
 
 	rc = do_readv_writev(ORANGEFS_IO_WRITE,
 			     file,
--- a/fs/orangefs/orangefs-kernel.h
+++ b/fs/orangefs/orangefs-kernel.h
@@ -570,17 +570,6 @@ do {									\
 	sys_attr.mask = ORANGEFS_ATTR_SYS_ALL_SETABLE;			\
 } while (0)
 
-static inline void orangefs_i_size_write(struct inode *inode, loff_t i_size)
-{
-#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
-	inode_lock(inode);
-#endif
-	i_size_write(inode, i_size);
-#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
-	inode_unlock(inode);
-#endif
-}
-
 static inline void orangefs_set_timeout(struct dentry *dentry)
 {
 	unsigned long time = jiffies + orangefs_dcache_timeout_msecs*HZ/1000;


Patches currently in stable-queue which might be from martin@omnibond.com are

queue-4.9/orangefs-fix-deadlock-do-not-write-i_size-in-read_iter.patch
queue-4.9/orangefs-initialize-op-on-loop-restart-in-orangefs_devreq_read.patch
queue-4.9/orangefs-use-list_for_each_entry_safe-in-purge_waiting_ops.patch