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authorDavid Howells <dhowells@redhat.com>2015-06-18 14:32:31 +0100
committerAl Viro <viro@zeniv.linux.org.uk>2015-06-19 03:19:32 -0400
commit4bacc9c9234c7c8eec44f5ed4e960d9f96fa0f01 (patch)
tree1ecac38332d4e8cf5370627f1214a1d7c5ff7529 /fs/open.c
parentf25801ee4680ef1db21e15c112e6e5fe3ffe8da5 (diff)
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overlayfs: Make f_path always point to the overlay and f_inode to the underlay
Make file->f_path always point to the overlay dentry so that the path in /proc/pid/fd is correct and to ensure that label-based LSMs have access to the overlay as well as the underlay (path-based LSMs probably don't need it). Using my union testsuite to set things up, before the patch I see: [root@andromeda union-testsuite]# bash 5</mnt/a/foo107 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ ... lr-x------. 1 root root 64 Jun 5 14:38 5 -> /a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 13381 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 13381 Links: 1 ... After the patch: [root@andromeda union-testsuite]# bash 5</mnt/a/foo107 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ ... lr-x------. 1 root root 64 Jun 5 14:22 5 -> /mnt/a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 40346 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 40346 Links: 1 ... Note the change in where /proc/$$/fd/5 points to in the ls command. It was pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107 (which is correct). The inode accessed, however, is the lower layer. The union layer is on device 25h/37d and the upper layer on 24h/36d. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c49
1 files changed, 26 insertions, 23 deletions
diff --git a/fs/open.c b/fs/open.c
index e0250bdcc440..b1c5823b7f11 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -678,18 +678,18 @@ int open_check_o_direct(struct file *f)
}
static int do_dentry_open(struct file *f,
+ struct inode *inode,
int (*open)(struct inode *, struct file *),
const struct cred *cred)
{
static const struct file_operations empty_fops = {};
- struct inode *inode;
int error;
f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
FMODE_PREAD | FMODE_PWRITE;
path_get(&f->f_path);
- inode = f->f_inode = f->f_path.dentry->d_inode;
+ f->f_inode = inode;
f->f_mapping = inode->i_mapping;
if (unlikely(f->f_flags & O_PATH)) {
@@ -793,7 +793,8 @@ int finish_open(struct file *file, struct dentry *dentry,
BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
file->f_path.dentry = dentry;
- error = do_dentry_open(file, open, current_cred());
+ error = do_dentry_open(file, d_backing_inode(dentry), open,
+ current_cred());
if (!error)
*opened |= FILE_OPENED;
@@ -822,6 +823,28 @@ int finish_no_open(struct file *file, struct dentry *dentry)
}
EXPORT_SYMBOL(finish_no_open);
+/**
+ * vfs_open - open the file at the given path
+ * @path: path to open
+ * @file: newly allocated file with f_flag initialized
+ * @cred: credentials to use
+ */
+int vfs_open(const struct path *path, struct file *file,
+ const struct cred *cred)
+{
+ struct dentry *dentry = path->dentry;
+ struct inode *inode = dentry->d_inode;
+
+ file->f_path = *path;
+ if (dentry->d_flags & DCACHE_OP_SELECT_INODE) {
+ inode = dentry->d_op->d_select_inode(dentry, file->f_flags);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+ }
+
+ return do_dentry_open(file, inode, NULL, cred);
+}
+
struct file *dentry_open(const struct path *path, int flags,
const struct cred *cred)
{
@@ -853,26 +876,6 @@ struct file *dentry_open(const struct path *path, int flags,
}
EXPORT_SYMBOL(dentry_open);
-/**
- * vfs_open - open the file at the given path
- * @path: path to open
- * @filp: newly allocated file with f_flag initialized
- * @cred: credentials to use
- */
-int vfs_open(const struct path *path, struct file *filp,
- const struct cred *cred)
-{
- struct inode *inode = path->dentry->d_inode;
-
- if (inode->i_op->dentry_open)
- return inode->i_op->dentry_open(path->dentry, filp, cred);
- else {
- filp->f_path = *path;
- return do_dentry_open(filp, NULL, cred);
- }
-}
-EXPORT_SYMBOL(vfs_open);
-
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
{
int lookup_flags = 0;