10:09 a.m.
On 5/9/19 7:20 PM, katcherw(a)gmail.com wrote:
I'm developing a proprietary FSAL in Ganesha 2.6.3. When using
NFSv3, I see that nfs3_create calls open2, which presumably is supposed to create the file
and open it. My question is when does the file get closed? I have a huge amount of open
files in my FSAL and not sure how to close them. Even in VFS, I see that created files
stay open.
For NFSv3, there isn't an explicit close in the protocol. This leaves
servers with two choices: close the file every time, and incur the
overhead of opening it every time, or cache the opens for a while, and
close them later. This is what Ganesha does. MDCACHE has a 2 layer LRU
that keeps track entries. When an entry transitions from L1 to L2 of
the LRU, it's open file handle is closed. This is done in the
background by a scrub thread, and is governed by a high-water and
low-water mark on the number of FDs, configured by FD_HWMark_Percent and
FD_LWMark_Percent. When lwmark is passed, the thread wakes up; when
hwmark is passed, it runs really hard. There's a hard limit, detected
at startup from the system rlimit. Percentages are relative to this.
Long story short: NFSv4 files will generally be closed when the client
is done; NFSv3 files will hang around
Daniel