[PATCH 26/60] staging: lustre: llite: Trust creates in revalidate too.
From: James Simmons
Date: Sat Jan 28 2017 - 19:12:58 EST
From: Oleg Drokin <oleg.drokin@xxxxxxxxx>
By forcing creates to always go via lookup we lose some
important caching benefits too.
Instead let's trust creates with positive cached entries.
Then we have 3 possible outcomes:
1. Negative dentry - we go via atomic_open and do the create
by name there.
2. Positive dentry, no contention - we just go straight to
ll_intent_file_open and open by fid.
3. positive dentry, contention - by the time we reach the server,
the inode is gone. We get ENOENT which is unacceptable to return
from create. But since we know it's a create, we substitute it
with ESTALE and VFS retries again with LOOKUP_REVAL set, we catch
that in revalidate and force a lookup (same path as before this
Signed-off-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Reviewed-by: James Simmons <uja.ornl@xxxxxxxxx>
Reviewed-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
drivers/staging/lustre/lustre/llite/dcache.c | 13 +++++--------
drivers/staging/lustre/lustre/llite/file.c | 11 +++++++++++
2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/drivers/staging/lustre/lustre/llite/dcache.c b/drivers/staging/lustre/lustre/llite/dcache.c
index 65bf0c4..966f580 100644
@@ -247,17 +247,14 @@ static int ll_revalidate_dentry(struct dentry *dentry,
- * if open&create is set, talk to MDS to make sure file is created if
- * necessary, because we can't do this in ->open() later since that's
- * called on an inode. return 0 here to let lookup to handle this.
+ * VFS warns us that this is the second go around and previous
+ * operation failed (most likely open|creat), so this time
+ * we better talk to the server via the lookup path by name,
+ * not by fid.
- if ((lookup_flags & (LOOKUP_OPEN | LOOKUP_CREATE)) ==
- (LOOKUP_OPEN | LOOKUP_CREATE))
+ if (lookup_flags & LOOKUP_REVAL)
- if (lookup_flags & (LOOKUP_PARENT | LOOKUP_OPEN | LOOKUP_CREATE))
- return 1;
if (!dentry_may_statahead(dir, dentry))
diff --git a/drivers/staging/lustre/lustre/llite/file.c b/drivers/staging/lustre/lustre/llite/file.c
index b681e15..0c83bd7 100644
@@ -417,6 +417,17 @@ static int ll_intent_file_open(struct dentry *de, void *lmm, int lmmsize,
+ * We did open by fid, but by the time we got to the server,
+ * the object disappeared. If this is a create, we cannot really
+ * tell the userspace that the file it was trying to create
+ * does not exist. Instead let's return -ESTALE, and the VFS will
+ * retry the create with LOOKUP_REVAL that we are going to catch
+ * in ll_revalidate_dentry() and use lookup then.
+ if (rc == -ENOENT && itp->it_op & IT_CREAT)
+ rc = -ESTALE;