From: Scott Mayhew smayhew@redhat.com
[ Upstream commit 0c8c7c559740d2d8b66048162af6c4dba8f0c88c ]
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 smayhew@redhat.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 bdd6cb33a3708..375c08fdcf2f3 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