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Subject[PATCH 16/73] VFS: Basic fallthru definitions [ver #2]
Date
From: Valerie Aurora <vaurora@redhat.com>

Define the fallthru dcache flag and file system op. Mask out the
DCACHE_FALLTHRU flag on dentry creation.

Actual users and changes to lookup come in later patches.

Signed-off-by: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

Documentation/filesystems/vfs.txt | 6 ++++++
fs/dcache.c | 2 +-
include/linux/dcache.h | 7 +++++++
include/linux/fs.h | 2 ++
4 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 8575c5b..6d9c108 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -350,6 +350,7 @@ struct inode_operations {
int (*rmdir) (struct inode *,struct dentry *);
int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
int (*whiteout) (struct inode *, struct dentry *, struct dentry *);
+ int (*fallthru) (struct inode *, struct dentry *);
int (*rename) (struct inode *, struct dentry *,
struct inode *, struct dentry *);
int (*readlink) (struct dentry *, char __user *,int);
@@ -421,6 +422,11 @@ otherwise noted.
second is the dentry for the whiteout itself. This method
must unlink() or rmdir() the original entry if it exists.

+ fallthru: called by the readdir(2) system call on a layered file
+ system. Only required if you want to support fallthrus.
+ Fallthrus are place-holders for directory entries visible from
+ a lower level file system.
+
rename: called by the rename(2) system call to rename the object to
have the parent and name given by the second inode and dentry.

diff --git a/fs/dcache.c b/fs/dcache.c
index 60af7b1..b1ce8d1 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1311,7 +1311,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
spin_lock(&dentry->d_lock);
if (inode) {
- dentry->d_flags &= ~DCACHE_WHITEOUT;
+ dentry->d_flags &= ~(DCACHE_WHITEOUT | DCACHE_FALLTHRU);
if (unlikely(IS_AUTOMOUNT(inode)))
dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
list_add(&dentry->d_alias, &inode->i_dentry);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f22f530..cc0181b 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -213,6 +213,8 @@ struct dentry_operations {
#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
/* Parent inode is watched by some fsnotify listener */

+#define DCACHE_FALLTHRU 0x8000 /* Continue lookup below an opaque dir */
+
#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
@@ -420,6 +422,11 @@ static inline int d_is_whiteout(struct dentry *dentry)
return dentry->d_flags & DCACHE_WHITEOUT;
}

+static inline int d_is_fallthru(struct dentry *dentry)
+{
+ return dentry->d_flags & DCACHE_FALLTHRU;
+}
+
static inline bool d_mountpoint(struct dentry *dentry)
{
return dentry->d_flags & DCACHE_MOUNTED;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1e4ae06..b5e6658 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -211,6 +211,7 @@ struct inodes_stat_t {
#define MS_I_VERSION (1<<23) /* Update inode I_version field */
#define MS_STRICTATIME (1<<24) /* Always perform atime updates */
#define MS_WHITEOUT (1<<25) /* FS supports whiteout filetype */
+#define MS_FALLTHRU (1<<26) /* FS supports fallthru filetype */
#define MS_NOSEC (1<<28)
#define MS_BORN (1<<29)
#define MS_ACTIVE (1<<30)
@@ -1653,6 +1654,7 @@ struct inode_operations {
int (*rmdir) (struct inode *,struct dentry *);
int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
int (*whiteout) (struct inode *, struct dentry *, struct dentry *);
+ int (*fallthru) (struct inode *, struct dentry *);
int (*rename) (struct inode *, struct dentry *,
struct inode *, struct dentry *);
void (*truncate) (struct inode *);


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