Commit ff7a5fb0 authored Jun 07, 2017 by Peter Zijlstra Committed by Ingo Molnar Aug 10, 2017

overlayfs, locking: Remove smp_mb__before_spinlock() usage



While we could replace the smp_mb__before_spinlock() with the new
smp_mb__after_spinlock(), the normal pattern is to use
smp_store_release() to publish an object that is used for
lockless_dereference() -- and mirrors the regular rcu_assign_pointer()
/ rcu_dereference() patterns.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 8b1b436d

fs/overlayfs/readdir.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -446,14 +446,14 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,

		ovl_path_upper(dentry, &upperpath);
		realfile = ovl_path_open(&upperpath, O_RDONLY);
		smp_mb__before_spinlock();

		inode_lock(inode);
		if (!od->upperfile) {
		if (IS_ERR(realfile)) {
		inode_unlock(inode);
		return PTR_ERR(realfile);
		}
		od->upperfile = realfile;
		smp_store_release(&od->upperfile, realfile);
		} else {
		/* somebody has beaten us to it */
		if (!IS_ERR(realfile))