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authorAl Viro <viro@ZenIV.linux.org.uk>2011-11-07 21:21:26 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-07 14:58:06 -0800
commita3fbbde70a0cec017f2431e8f8de208708c76acc (patch)
treef584856e638ca916a8aca32eda58a8fe89722c9f
parent54a0f91301950af3d6ae2ff2bf710c9c68a9bfea (diff)
downloadconfigs-a3fbbde70a0cec017f2431e8f8de208708c76acc.tar.gz
VFS: we need to set LOOKUP_JUMPED on mountpoint crossing
Mountpoint crossing is similar to following procfs symlinks - we do not get ->d_revalidate() called for dentry we have arrived at, with unpleasant consequences for NFS4. Simple way to reproduce the problem in mainline: cat >/tmp/a.c <<'EOF' #include <unistd.h> #include <fcntl.h> #include <stdio.h> main() { struct flock fl = {.l_type = F_RDLCK, .l_whence = SEEK_SET, .l_len = 1}; if (fcntl(0, F_SETLK, &fl)) perror("setlk"); } EOF cc /tmp/a.c -o /tmp/test then on nfs4: mount --bind file1 file2 /tmp/test < file1 # ok /tmp/test < file2 # spews "setlk: No locks available"... What happens is the missing call of ->d_revalidate() after mountpoint crossing and that's where NFS4 would issue OPEN request to server. The fix is simple - treat mountpoint crossing the same way we deal with following procfs-style symlinks. I.e. set LOOKUP_JUMPED... Cc: stable@kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/namei.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/fs/namei.c b/fs/namei.c
index ac6d214da82..5008f01787f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -852,7 +852,7 @@ static int follow_managed(struct path *path, unsigned flags)
mntput(path->mnt);
if (ret == -EISDIR)
ret = 0;
- return ret;
+ return ret < 0 ? ret : need_mntput;
}
int follow_down_one(struct path *path)
@@ -900,6 +900,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
break;
path->mnt = mounted;
path->dentry = mounted->mnt_root;
+ nd->flags |= LOOKUP_JUMPED;
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
/*
* Update the inode too. We don't need to re-check the
@@ -1213,6 +1214,8 @@ retry:
path_put_conditional(path, nd);
return err;
}
+ if (err)
+ nd->flags |= LOOKUP_JUMPED;
*inode = path->dentry->d_inode;
return 0;
}
@@ -2146,6 +2149,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
}
/* create side of things */
+ /*
+ * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been
+ * cleared when we got to the last component we are about to look up
+ */
error = complete_walk(nd);
if (error)
return ERR_PTR(error);
@@ -2214,6 +2221,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
if (error < 0)
goto exit_dput;
+ if (error)
+ nd->flags |= LOOKUP_JUMPED;
+
error = -ENOENT;
if (!path->dentry->d_inode)
goto exit_dput;
@@ -2223,6 +2233,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
path_to_nameidata(path, nd);
nd->inode = path->dentry->d_inode;
+ /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
+ error = complete_walk(nd);
+ if (error)
+ goto exit;
error = -EISDIR;
if (S_ISDIR(nd->inode->i_mode))
goto exit;