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authorJeff Layton <jlayton@redhat.com>2017-12-18 06:25:31 -0500
committerJeff Layton <jlayton@redhat.com>2018-01-29 06:42:20 -0500
commit7594c461161745f0d38a4346d4f895e0837b8094 (patch)
treeb1469f3097ad6116405bb7a014c097c59ad947b2
parentae5e165d855dd978a461b22175531b07f54fb61f (diff)
fs: don't take the i_lock in inode_inc_iversion
The rationale for taking the i_lock when incrementing this value is lost in antiquity. The readers of the field don't take it (at least not universally), so my assumption is that it was only done here to serialize incrementors. If that is indeed the case, then we can drop the i_lock from this codepath and treat it as a atomic64_t for the purposes of incrementing it. This allows us to use inode_inc_iversion without any danger of lock inversion. Note that the read side is not fetched atomically with this change. The assumption here is that that is not a critical issue since the i_version is not fully synchronized with anything else anyway. Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz>
-rw-r--r--include/linux/iversion.h7
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/iversion.h b/include/linux/iversion.h
index d61e063f7c75..f268828f9f7e 100644
--- a/include/linux/iversion.h
+++ b/include/linux/iversion.h
@@ -110,12 +110,13 @@ inode_set_iversion_queried(struct inode *inode, u64 new)
static inline bool
inode_maybe_inc_iversion(struct inode *inode, bool force)
{
- spin_lock(&inode->i_lock);
- inode->i_version++;
- spin_unlock(&inode->i_lock);
+ atomic64_t *ivp = (atomic64_t *)&inode->i_version;
+
+ atomic64_inc(ivp);
return true;
}
+
/**
* inode_inc_iversion - forcibly increment i_version
* @inode: inode that needs to be updated