From a1147b8281bda99bda99892233e1900329a9cbf1 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 5 Feb 2020 09:01:52 -0500 Subject: [PATCH] NFS: Fix up directory verifier races In order to avoid having our dentry revalidation race with an update of the directory on the server, we need to store the verifier before the RPC calls to LOOKUP and READDIR. Signed-off-by: Trond Myklebust Reviewed-by: Benjamin Coddington Tested-by: Benjamin Coddington Signed-off-by: Anna Schumaker --- fs/nfs/dir.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 1320288ff9ec..b4e7558e42ab 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -155,6 +155,7 @@ typedef struct { loff_t current_index; decode_dirent_t decode; + unsigned long dir_verifier; unsigned long timestamp; unsigned long gencount; unsigned int cache_entry_index; @@ -353,6 +354,7 @@ int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc, again: timestamp = jiffies; gencount = nfs_inc_attr_generation_counter(); + desc->dir_verifier = nfs_save_change_attribute(inode); error = NFS_PROTO(inode)->readdir(file_dentry(file), cred, entry->cookie, pages, NFS_SERVER(inode)->dtsize, desc->plus); if (error < 0) { @@ -455,13 +457,13 @@ void nfs_force_use_readdirplus(struct inode *dir) } static -void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) +void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry, + unsigned long dir_verifier) { struct qstr filename = QSTR_INIT(entry->name, entry->len); DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); struct dentry *dentry; struct dentry *alias; - struct inode *dir = d_inode(parent); struct inode *inode; int status; @@ -500,7 +502,7 @@ again: if (nfs_same_file(dentry, entry)) { if (!entry->fh->size) goto out; - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); + nfs_set_verifier(dentry, dir_verifier); status = nfs_refresh_inode(d_inode(dentry), entry->fattr); if (!status) nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label); @@ -526,7 +528,7 @@ again: dput(dentry); dentry = alias; } - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); + nfs_set_verifier(dentry, dir_verifier); out: dput(dentry); } @@ -564,7 +566,8 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en count++; if (desc->plus) - nfs_prime_dcache(file_dentry(desc->file), entry); + nfs_prime_dcache(file_dentry(desc->file), entry, + desc->dir_verifier); status = nfs_readdir_add_to_array(entry, page); if (status != 0) @@ -1159,6 +1162,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, struct nfs_fh *fhandle; struct nfs_fattr *fattr; struct nfs4_label *label; + unsigned long dir_verifier; int ret; ret = -ENOMEM; @@ -1168,6 +1172,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, if (fhandle == NULL || fattr == NULL || IS_ERR(label)) goto out; + dir_verifier = nfs_save_change_attribute(dir); ret = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label); if (ret < 0) { switch (ret) { @@ -1188,7 +1193,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, goto out; nfs_setsecurity(inode, fattr, label); - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); + nfs_set_verifier(dentry, dir_verifier); /* set a readdirplus hint that we had a cache miss */ nfs_force_use_readdirplus(dir); @@ -1415,6 +1420,7 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in struct nfs_fh *fhandle = NULL; struct nfs_fattr *fattr = NULL; struct nfs4_label *label = NULL; + unsigned long dir_verifier; int error; dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry); @@ -1440,6 +1446,7 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in if (IS_ERR(label)) goto out; + dir_verifier = nfs_save_change_attribute(dir); trace_nfs_lookup_enter(dir, dentry, flags); error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label); if (error == -ENOENT) @@ -1463,7 +1470,7 @@ no_entry: goto out_label; dentry = res; } - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); + nfs_set_verifier(dentry, dir_verifier); out_label: trace_nfs_lookup_exit(dir, dentry, flags, error); nfs4_label_free(label); -- 2.30.2