[PATCH] Fix deadlock on regular nonseekable files

[Vitaly Chernooky]

'Commit 9c225f2655e36a470c4f58dbbc99244c5fc7f2d4 ("vfs: atomic f_pos
accesses as per POSIX")' introduce following regression. If some program
does multithreaded IO on file in pseudo-filesystem, like procfs, with
nonseekable files marked as regular, we get deadlock on f_pos_lock
mutex, if there are simultaneous reading and writing by different
threads.

Signed-off-by: Vitaly Chernooky <vitaly.chernooky@xxxxxxxxxxxxxxx>
---
 fs/open.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index 33f9cbf..1a4f84b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1135,7 +1135,7 @@ EXPORT_SYMBOL(generic_file_open);
  */
 int nonseekable_open(struct inode *inode, struct file *filp)
 {
- filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
+ filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE |
FMODE_ATOMIC_POS);
  return 0;
 }

-- 
1.7.9.5

With best regards,

-- 
Vitaly Chernooky | Senior Developer - Product Engineering and Development
GlobalLogic
P +380.44.4929695 ext.1136 M +380.63.6011802 S cvv_2k
www.globallogic.com

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