[LU-560] negative dentries not cached after open, even with MDS_INODELOCK_UPDATE on parent

Tue, 16 Aug 2011 13:47:50 +0000

Trying to open a non-existent file does not cause a negative dentry to be cached, even
when parent ctime is more than ctime_age_limit (10) seconds old, or even when MDS_INODELOCK_UPDATE is held.

To reproduce:

/usr/lib64/lustre/tests/llmount.sh
echo +dentry +inode +dlmtrace +vfstrace +rpctrace > /proc/sys/lnet/debug
lctl clear
mkdir /mnt/lustre/DDD
sleep 20 # Twice ctime_age_limit.
cat /mnt/lustre/DDD/XXX
cat /mnt/lustre/DDD/XXX
lctl dk negative-dentry-not-cached.log

Then negative-dentry-not-cached.log shows an LDLM_ENQUEUE being sent for each open.

Alternatively, stating a non-existent file will cache a negative dentry, but opens on other non-existent files in the same directory will not cache negative dentries, see stat-vs-open.txt.

Whamcloud Community JIRA

[LU-560] negative dentries not cached after open, even with MDS_INODELOCK_UPDATE on parent