From 862e4c3a4b0083da12667b155150afc9cdec66b2 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 5 Feb 2020 09:01:53 -0500 Subject: [PATCH] NFSv4: Fix races between open and dentry revalidation [ Upstream commit cf5b4059ba7197d6cef9c0e024979d178ed8c8ec ] We want to make sure that we revalidate the dentry if and only if we've done an OPEN by filename. In order to avoid races with remote changes to the directory on the server, we want to save the verifier before calling OPEN. The exception is if the server returned a delegation with our OPEN, as we then know that the filename can't have changed on the server. Signed-off-by: Trond Myklebust Reviewed-by: Benjamin Coddington Tested-by: Benjamin Coddington Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- fs/nfs/nfs4file.c | 1 - fs/nfs/nfs4proc.c | 18 ++++++++++++++++-- 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c index 339663d04bf8..54f1c1f626fc 100644 --- a/fs/nfs/nfs4file.c +++ b/fs/nfs/nfs4file.c @@ -86,7 +86,6 @@ nfs4_file_open(struct inode *inode, struct file *filp) if (inode != d_inode(dentry)) goto out_drop; - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); nfs_file_set_open_context(filp, ctx); nfs_fscache_open_file(inode, filp); err = 0; diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index f808fb34b110..6b29703d2fe1 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -2962,10 +2962,13 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata, struct dentry *dentry; struct nfs4_state *state; fmode_t acc_mode = _nfs4_ctx_to_accessmode(ctx); + struct inode *dir = d_inode(opendata->dir); + unsigned long dir_verifier; unsigned int seq; int ret; seq = raw_seqcount_begin(&sp->so_reclaim_seqcount); + dir_verifier = nfs_save_change_attribute(dir); ret = _nfs4_proc_open(opendata, ctx); if (ret != 0) @@ -2993,8 +2996,19 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata, dput(ctx->dentry); ctx->dentry = dentry = alias; } - nfs_set_verifier(dentry, - nfs_save_change_attribute(d_inode(opendata->dir))); + } + + switch(opendata->o_arg.claim) { + default: + break; + case NFS4_OPEN_CLAIM_NULL: + case NFS4_OPEN_CLAIM_DELEGATE_CUR: + case NFS4_OPEN_CLAIM_DELEGATE_PREV: + if (!opendata->rpc_done) + break; + if (opendata->o_res.delegation_type != 0) + dir_verifier = nfs_save_change_attribute(dir); + nfs_set_verifier(dentry, dir_verifier); } /* Parse layoutget results before we check for access */