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NFSv4: Fix lookup revalidate of regular files

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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>
This commit is contained in:
Trond Myklebust 2018-09-28 12:42:51 -04:00
parent 5ceb9d7fda
commit c7944ebb9c
1 changed files with 38 additions and 39 deletions
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77
fs/nfs/dir.c
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@ -1231,7 +1231,8 @@ nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
} }
static int 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 dentry *parent;
struct inode *dir; struct inode *dir;
@ -1242,17 +1243,22 @@ nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
dir = d_inode_rcu(parent); dir = d_inode_rcu(parent);
if (!dir) if (!dir)
return -ECHILD; return -ECHILD;
ret = nfs_do_lookup_revalidate(dir, dentry, flags); ret = reval(dir, dentry, flags);
if (parent != READ_ONCE(dentry->d_parent)) if (parent != READ_ONCE(dentry->d_parent))
return -ECHILD; return -ECHILD;
} else { } else {
parent = dget_parent(dentry); parent = dget_parent(dentry);
ret = nfs_do_lookup_revalidate(d_inode(parent), dentry, flags); ret = reval(d_inode(parent), dentry, flags);
dput(parent); dput(parent);
} }
return ret; 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) * 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 * when we don't really care about the dentry name. This is called when a
@ -1609,62 +1615,55 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
} }
EXPORT_SYMBOL_GPL(nfs_atomic_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; struct inode *inode;
int ret = 0;
if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY)) if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
goto no_open; goto full_reval;
if (d_mountpoint(dentry)) if (d_mountpoint(dentry))
goto no_open; goto full_reval;
if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)
goto no_open;
inode = d_inode(dentry); inode = d_inode(dentry);
/* We can't create new files in nfs_open_revalidate(), so we /* We can't create new files in nfs_open_revalidate(), so we
* optimize away revalidation of negative dentries. * optimize away revalidation of negative dentries.
*/ */
if (inode == NULL) { if (inode == NULL)
struct dentry *parent; goto full_reval;
struct inode *dir;
if (flags & LOOKUP_RCU) { if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
parent = READ_ONCE(dentry->d_parent); return nfs_lookup_revalidate_delegated(dir, dentry, inode);
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;
}
/* NFS only supports OPEN on regular files */ /* NFS only supports OPEN on regular files */
if (!S_ISREG(inode->i_mode)) if (!S_ISREG(inode->i_mode))
goto no_open; goto full_reval;
/* We cannot do exclusive creation on a positive dentry */ /* We cannot do exclusive creation on a positive dentry */
if (flags & LOOKUP_EXCL) if (flags & (LOOKUP_EXCL | LOOKUP_REVAL))
goto no_open; 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 */ /* 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: full_reval:
return ret; return nfs_do_lookup_revalidate(dir, dentry, flags);
}
no_open: static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
return nfs_lookup_revalidate(dentry, flags); {
return __nfs_lookup_revalidate(dentry, flags,
nfs4_do_lookup_revalidate);
} }
#endif /* CONFIG_NFSV4 */ #endif /* CONFIG_NFSV4 */