This is a slight variation on a patch previously proposed by Neil Brown
that never got merged.
Prior to commit 5ceb9d7fdaaf ("NFS: Refactor nfs_lookup_revalidate()"),
any error from nfs_lookup_verify_inode() other than -ESTALE would result
in nfs_lookup_revalidate() returning that error (-ESTALE is mapped to
zero).
Since that commit, all errors result in nfs_lookup_revalidate()
returning zero, resulting in dentries being invalidated where they
previously were not (particularly in the case of -ERESTARTSYS).
Fix it by passing the actual error code to nfs_lookup_revalidate_done(),
and leaving the decision on whether to map the error code to zero or
one to nfs_lookup_revalidate_done().
A simple reproducer is to run the following python code in a
subdirectory of an NFS mount (not in the root of the NFS mount):
---8<---
import os
import multiprocessing
import time
if __name__=="__main__":
multiprocessing.set_start_method("spawn")
count = 0
while True:
try:
os.getcwd()
pool = multiprocessing.Pool(10)
pool.close()
pool.terminate()
count += 1
except Exception as e:
print(f"Failed after {count} iterations")
print(e)
break
---8<---
Prior to commit 5ceb9d7fdaaf, the above code would run indefinitely.
After commit 5ceb9d7fdaaf, it fails almost immediately with -ENOENT.
Signed-off-by: Scott Mayhew <[email protected]>
---
v2: Don't skip the special handling of root dentries on error <= 0
in nfs_lookup_revalidate_done().
fs/nfs/dir.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ac505671efbd..feed8d89bee1 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1625,7 +1625,16 @@ nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
switch (error) {
case 1:
break;
- case 0:
+ case -ETIMEDOUT:
+ if (inode && (IS_ROOT(dentry) ||
+ NFS_SERVER(inode)->flags & NFS_MOUNT_SOFTREVAL))
+ error = 1;
+ break;
+ case -ESTALE:
+ case -ENOENT:
+ error = 0;
+ fallthrough;
+ default:
/*
* We can't d_drop the root of a disconnected tree:
* its d_hash is on the s_anon list and d_drop() would hide
@@ -1680,18 +1689,8 @@ static int nfs_lookup_revalidate_dentry(struct inode *dir,
dir_verifier = nfs_save_change_attribute(dir);
ret = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr);
- if (ret < 0) {
- switch (ret) {
- case -ESTALE:
- case -ENOENT:
- ret = 0;
- break;
- case -ETIMEDOUT:
- if (NFS_SERVER(inode)->flags & NFS_MOUNT_SOFTREVAL)
- ret = 1;
- }
+ if (ret < 0)
goto out;
- }
/* Request help from readdirplus */
nfs_lookup_advise_force_readdirplus(dir, flags);
@@ -1735,7 +1734,7 @@ nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct inode *inode;
- int error;
+ int error = 0;
nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
inode = d_inode(dentry);
@@ -1780,7 +1779,7 @@ nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
out_bad:
if (flags & LOOKUP_RCU)
return -ECHILD;
- return nfs_lookup_revalidate_done(dir, dentry, inode, 0);
+ return nfs_lookup_revalidate_done(dir, dentry, inode, error);
}
static int
--
2.44.0