diff options
| author | Al Viro <viro@ZenIV.linux.org.uk> | 2011-11-07 21:21:26 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-11 09:37:08 -0800 |
| commit | 656460cd7714653cf60a10c79e02cbfe2d9bf732 (patch) | |
| tree | a9eb6dd3de35c760ae5d327fd121a7e0ce78c8fb /fs | |
| parent | 0447f4d5654bb5d95008f16dad839104f8d0d39a (diff) | |
VFS: we need to set LOOKUP_JUMPED on mountpoint crossing
commit a3fbbde70a0cec017f2431e8f8de208708c76acc upstream.
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...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namei.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/fs/namei.c b/fs/namei.c index 49472a1b79e..f7593c0899d 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -910,7 +910,7 @@ 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) @@ -958,6 +958,7 @@ 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 @@ -1232,6 +1233,8 @@ retry: path_put_conditional(path, nd); return err; } + if (err) + nd->flags |= LOOKUP_JUMPED; *inode = path->dentry->d_inode; return 0; } @@ -2118,6 +2121,10 @@ 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); @@ -2186,6 +2193,9 @@ 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; @@ -2195,6 +2205,10 @@ 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; |