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fsnotify: store struct file not struct path

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Al explains that calling dentry_open() with a mnt/dentry pair is only
garunteed to be safe if they are already used in an open struct file.  To
make sure this is the case don't store and use a struct path in fsnotify,
always use a struct file.

Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris 2010-07-28 10:18:37 -04:00
commit 3bcf3860a4
8 changed files with 56 additions and 63 deletions
Download patch file Download diff file Expand all files Collapse all files

37
include/linux/fsnotify.h
View file

@ -26,19 +26,18 @@ static inline void fsnotify_d_instantiate(struct dentry *dentry,
}
/* Notify this dentry's parent about a child's events. */
static inline void fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
static inline void fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
{
if (!dentry)
dentry = path->dentry;
dentry = file->f_path.dentry;
__fsnotify_parent(path, dentry, mask);
__fsnotify_parent(file, dentry, mask);
}
/* simple call site for access decisions */
static inline int fsnotify_perm(struct file *file, int mask)
{
struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file->f_path.dentry->d_inode;
__u32 fsnotify_mask = 0;
if (file->f_mode & FMODE_NONOTIFY)
@ -52,7 +51,7 @@ static inline int fsnotify_perm(struct file *file, int mask)
else
BUG();
return fsnotify(inode, fsnotify_mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
return fsnotify(inode, fsnotify_mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
}
/*
@ -187,16 +186,15 @@ static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
*/
static inline void fsnotify_access(struct file *file)
{
struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file->f_path.dentry->d_inode;
__u32 mask = FS_ACCESS;
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
if (!(file->f_mode & FMODE_NONOTIFY)) {
fsnotify_parent(path, NULL, mask);
fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
fsnotify_parent(file, NULL, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
}
}
@ -205,16 +203,15 @@ static inline void fsnotify_access(struct file *file)
*/
static inline void fsnotify_modify(struct file *file)
{
struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file->f_path.dentry->d_inode;
__u32 mask = FS_MODIFY;
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
if (!(file->f_mode & FMODE_NONOTIFY)) {
fsnotify_parent(path, NULL, mask);
fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
fsnotify_parent(file, NULL, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
}
}
@ -223,16 +220,15 @@ static inline void fsnotify_modify(struct file *file)
*/
static inline void fsnotify_open(struct file *file)
{
struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
struct inode *inode = file->f_path.dentry->d_inode;
__u32 mask = FS_OPEN;
if (S_ISDIR(inode->i_mode))
mask |= FS_IN_ISDIR;
if (!(file->f_mode & FMODE_NONOTIFY)) {
fsnotify_parent(path, NULL, mask);
fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
fsnotify_parent(file, NULL, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
}
}
@ -241,7 +237,6 @@ static inline void fsnotify_open(struct file *file)
*/
static inline void fsnotify_close(struct file *file)
{
struct path *path = &file->f_path;
struct inode *inode = file->f_path.dentry->d_inode;
fmode_t mode = file->f_mode;
__u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE;
@ -250,8 +245,8 @@ static inline void fsnotify_close(struct file *file)
mask |= FS_IN_ISDIR;
if (!(file->f_mode & FMODE_NONOTIFY)) {
fsnotify_parent(path, NULL, mask);
fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
fsnotify_parent(file, NULL, mask);
fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE, NULL, 0);
}
}

16
include/linux/fsnotify_backend.h
View file

@ -223,20 +223,20 @@ struct fsnotify_event {
/* to_tell may ONLY be dereferenced during handle_event(). */
struct inode *to_tell; /* either the inode the event happened to or its parent */
/*
* depending on the event type we should have either a path or inode
* We hold a reference on path, but NOT on inode. Since we have the ref on
* the path, it may be dereferenced at any point during this object's
* depending on the event type we should have either a file or inode
* We hold a reference on file, but NOT on inode. Since we have the ref on
* the file, it may be dereferenced at any point during this object's
* lifetime. That reference is dropped when this object's refcnt hits
* 0. If this event contains an inode instead of a path, the inode may
* 0. If this event contains an inode instead of a file, the inode may
* ONLY be used during handle_event().
*/
union {
struct path path;
struct file *file;
struct inode *inode;
};
/* when calling fsnotify tell it if the data is a path or inode */
#define FSNOTIFY_EVENT_NONE 0
#define FSNOTIFY_EVENT_PATH 1
#define FSNOTIFY_EVENT_FILE 1
#define FSNOTIFY_EVENT_INODE 2
int data_type; /* which of the above union we have */
atomic_t refcnt; /* how many groups still are using/need to send this event */
@ -311,7 +311,7 @@ struct fsnotify_mark {
/* main fsnotify call to send events */
extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
const unsigned char *name, u32 cookie);
extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
extern void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask);
extern void __fsnotify_inode_delete(struct inode *inode);
extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
extern u32 fsnotify_get_cookie(void);
@ -444,7 +444,7 @@ static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int da
return 0;
}
static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
static inline void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
{}
static inline void __fsnotify_inode_delete(struct inode *inode)