From: Oleg Drokin <oleg.dro...@intel.com> 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 patch). Signed-off-by: Oleg Drokin <oleg.dro...@intel.com> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8371 Reviewed-on: http://review.whamcloud.com/21168 Reviewed-by: James Simmons <uja.o...@yahoo.com> Reviewed-by: Andreas Dilger <andreas.dil...@intel.com> Signed-off-by: James Simmons <jsimm...@infradead.org> --- 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 --- a/drivers/staging/lustre/lustre/llite/dcache.c +++ b/drivers/staging/lustre/lustre/llite/dcache.c @@ -247,17 +247,14 @@ static int ll_revalidate_dentry(struct dentry *dentry, return 1; /* - * 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) return 0; - if (lookup_flags & (LOOKUP_PARENT | LOOKUP_OPEN | LOOKUP_CREATE)) - return 1; - if (!dentry_may_statahead(dir, dentry)) return 1; diff --git a/drivers/staging/lustre/lustre/llite/file.c b/drivers/staging/lustre/lustre/llite/file.c index b681e15..0c83bd7 100644 --- a/drivers/staging/lustre/lustre/llite/file.c +++ b/drivers/staging/lustre/lustre/llite/file.c @@ -417,6 +417,17 @@ static int ll_intent_file_open(struct dentry *de, void *lmm, int lmmsize, ptlrpc_req_finished(req); ll_intent_drop_lock(itp); + /* + * 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; + return rc; } -- 1.8.3.1 _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
