The following commit has been merged in the openafs-stable-1_6_x branch:
commit ef5fe95fdf4e063daafcfee4435f0f9026bf9ada
Author: Mark Vitale <[email protected]>
Date: Thu Nov 30 20:26:46 2017 -0500
LINUX: Avoid d_invalidate() during afs_ShakeLooseVCaches()
With recent changes to d_invalidate's semantics (it returns void in Linux
3.11,
and always returns success in RHEL 7.4), it has become increasingly clear
that
d_invalidate() is not the best function for use in our best-effort
(nondisruptive) attempt to free up vcaches that is afs_ShakeLooseVCaches().
The new d_invalidate() semantics always force the invalidation of a
directory
dentry, which contradicts our desire to be nondisruptive, especially when
that directory is being used as the current working directory for a process.
Our call to d_invalidate(), intended to merely probe for whether a dentry
can be discarded without affecting other consumers, instead would cause
processes using that dentry as a CWD to receive ENOENT errors from getcwd().
A previous commit (c3bbf0b4444db88192eea4580ac9e9ca3de0d286) tried to
address
this issue by calling d_prune_aliases() instead of d_invalidate(), but
d_prune_aliases() does not recursively descend into children of the given
dentry while pruning, leaving it an incomplete solution for our use-case.
To address these issues, modify the shakeloose routine TryEvictDentries() to
call shrink_dcache_parent() and maybe __d_drop() for directories, and
d_prune_aliases() for non-directories, instead of d_invalidate(). (Calls to
d_prune_aliases() for directories have already been removed by reverting
commit
c3bbf0b4444db88192eea4580ac9e9ca3de0d286.)
Just like d_invalidate(), shrink_dcache_parent() has been around "forever"
(since pre-git v2.6.12). Also like d_invalidate(), it "walks" the parent
dentry's subdirectories and "shrinks" (unhashes) unused dentries. But
unlike
d_invalidate(), shrink_dcache_parent() will not unhash an in-use dentry, and
has never changed its signature or semantics.
d_prune_aliases() has also been available "forever", and has also never
changed
its signature or semantics. The lack of recursive descent is not an issue
for
non-directories, which cannot have such children.
[[email protected]: apply review feedback to fix locking and avoid extraneous
changes, and reword commit message]
Reviewed-on: https://gerrit.openafs.org/12830
Reviewed-by: Benjamin Kaduk <[email protected]>
Tested-by: BuildBot <[email protected]>
(cherry picked from commit afbc199f152cc06edc877333f229604c28638d07)
Reviewed-on: https://gerrit.openafs.org/12851
Tested-by: BuildBot <[email protected]>
Tested-by: Benjamin Kaduk <[email protected]>
Reviewed-by: Benjamin Kaduk <[email protected]>
(cherry picked from commit 4feec06c7bdc7102ae654cff20eb02650ec32800)
Change-Id: Id509e51f027bd96df155e7ed714e0c7dfce126eb
Reviewed-on: https://gerrit.openafs.org/12860
Tested-by: BuildBot <[email protected]>
Reviewed-by: Andrew Deason <[email protected]>
Reviewed-by: Stephan Wiesand <[email protected]>
src/afs/LINUX/osi_vcache.c | 51 +++++++++++++++++++++++++++++++++++++------
1 files changed, 44 insertions(+), 7 deletions(-)
--
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