From: Trond Myklebust trond.myklebust@hammerspace.com
commit c7944ebb9ce9461079659e9e6ec5baaf73724b3b upstream.
If we're revalidating an existing dentry in order to open a file, we need to ensure that we check the directory has not changed before we optimise away the lookup.
Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Qian Lu luqia@amazon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/nfs/dir.c | 79 +++++++++++++++++++++++++++++------------------------------ 1 file changed, 39 insertions(+), 40 deletions(-)
--- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1231,7 +1231,8 @@ out_bad: }
static int -nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) +__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags, + int (*reval)(struct inode *, struct dentry *, unsigned int)) { struct dentry *parent; struct inode *dir; @@ -1242,17 +1243,22 @@ nfs_lookup_revalidate(struct dentry *den dir = d_inode_rcu(parent); if (!dir) return -ECHILD; - ret = nfs_do_lookup_revalidate(dir, dentry, flags); + ret = reval(dir, dentry, flags); if (parent != READ_ONCE(dentry->d_parent)) return -ECHILD; } else { parent = dget_parent(dentry); - ret = nfs_do_lookup_revalidate(d_inode(parent), dentry, flags); + ret = reval(d_inode(parent), dentry, flags); dput(parent); } return ret; }
+static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) +{ + return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate); +} + /* * A weaker form of d_revalidate for revalidating just the d_inode(dentry) * when we don't really care about the dentry name. This is called when a @@ -1609,62 +1615,55 @@ no_open: } EXPORT_SYMBOL_GPL(nfs_atomic_open);
-static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) +static int +nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry, + unsigned int flags) { struct inode *inode; - int ret = 0;
if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY)) - goto no_open; + goto full_reval; if (d_mountpoint(dentry)) - goto no_open; - if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1) - goto no_open; + goto full_reval;
inode = d_inode(dentry);
/* We can't create new files in nfs_open_revalidate(), so we * optimize away revalidation of negative dentries. */ - if (inode == NULL) { - struct dentry *parent; - struct inode *dir; - - if (flags & LOOKUP_RCU) { - parent = READ_ONCE(dentry->d_parent); - dir = d_inode_rcu(parent); - if (!dir) - return -ECHILD; - } else { - parent = dget_parent(dentry); - dir = d_inode(parent); - } - if (!nfs_neg_need_reval(dir, dentry, flags)) - ret = 1; - else if (flags & LOOKUP_RCU) - ret = -ECHILD; - if (!(flags & LOOKUP_RCU)) - dput(parent); - else if (parent != READ_ONCE(dentry->d_parent)) - return -ECHILD; - goto out; - } + if (inode == NULL) + goto full_reval; + + if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ)) + return nfs_lookup_revalidate_delegated(dir, dentry, inode);
/* NFS only supports OPEN on regular files */ if (!S_ISREG(inode->i_mode)) - goto no_open; + goto full_reval; + /* We cannot do exclusive creation on a positive dentry */ - if (flags & LOOKUP_EXCL) - goto no_open; + if (flags & (LOOKUP_EXCL | LOOKUP_REVAL)) + goto reval_dentry; + + /* Check if the directory changed */ + if (!nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) + goto reval_dentry;
/* Let f_op->open() actually open (and revalidate) the file */ - ret = 1; + return 1; +reval_dentry: + if (flags & LOOKUP_RCU) + return -ECHILD; + return nfs_lookup_revalidate_dentry(dir, dentry, inode);;
-out: - return ret; +full_reval: + return nfs_do_lookup_revalidate(dir, dentry, flags); +}
-no_open: - return nfs_lookup_revalidate(dentry, flags); +static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) +{ + return __nfs_lookup_revalidate(dentry, flags, + nfs4_do_lookup_revalidate); }
#endif /* CONFIG_NFSV4 */