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fsnotify(): switch to passing const struct qstr * for file_name

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Note that in fnsotify_move() and fsnotify_link() we are guaranteed
that dentry->d_name won't change during the fsnotify() evaluation
(by having the parent directory locked exclusive), so we don't
need to fetch dentry->d_name.name in the callers.  In fsnotify_dirent()
the same stability of dentry->d_name is also true, but it's a bit
more convoluted - there is one callchain (devpts_pty_new() ->
fsnotify_create() -> fsnotify_dirent()) where the parent is _not_
locked, but on devpts ->d_name of everything is unchanging; it
has neither explicit nor implicit renames.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-04-26 13:37:25 -04:00
parent f4ec3a3d43
commit 25b229dff4
4 changed files with 15 additions and 13 deletions
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6
fs/kernfs/file.c
View File

@ -885,6 +885,7 @@ repeat:
list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
struct kernfs_node *parent;
struct inode *inode;
struct qstr name;
/*
* We want fsnotify_modify() on @kn but as the
@ -896,6 +897,7 @@ repeat:
if (!inode)
continue;
name = (struct qstr)QSTR_INIT(kn->name, strlen(kn->name));
parent = kernfs_get_parent(kn);
if (parent) {
struct inode *p_inode;
@ -903,7 +905,7 @@ repeat:
p_inode = ilookup(info->sb, parent->id.ino);
if (p_inode) {
fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD,
inode, FSNOTIFY_EVENT_INODE, kn->name, 0);
inode, FSNOTIFY_EVENT_INODE, &name, 0);
iput(p_inode);
}
@ -911,7 +913,7 @@ repeat:
}
fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
kn->name, 0);
&name, 0);
iput(inode);
}

8
fs/notify/fsnotify.c
View File

@ -179,10 +179,10 @@ int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask
take_dentry_name_snapshot(&name, dentry);
if (path)
ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
name.name.name, 0);
&name.name, 0);
else
ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
name.name.name, 0);
&name.name, 0);
release_dentry_name_snapshot(&name);
}
@ -325,7 +325,7 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
* notification event in whatever means they feel necessary.
*/
int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
const unsigned char *file_name, u32 cookie)
const struct qstr *file_name, u32 cookie)
{
struct fsnotify_iter_info iter_info = {};
struct super_block *sb = to_tell->i_sb;
@ -379,7 +379,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
*/
while (fsnotify_iter_select_report_types(&iter_info)) {
ret = send_to_group(to_tell, mask, data, data_is, cookie,
file_name, &iter_info);
file_name->name, &iter_info);
if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
goto out;

10
include/linux/fsnotify.h
View File

@ -27,7 +27,7 @@ static inline int fsnotify_dirent(struct inode *dir, struct dentry *dentry,
__u32 mask)
{
return fsnotify(dir, mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
dentry->d_name.name, 0);
&dentry->d_name, 0);
}
/* Notify this dentry's parent about a child's events. */
@ -111,7 +111,7 @@ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
__u32 old_dir_mask = FS_MOVED_FROM;
__u32 new_dir_mask = FS_MOVED_TO;
__u32 mask = FS_MOVE_SELF;
const unsigned char *new_name = moved->d_name.name;
const struct qstr *new_name = &moved->d_name;
if (old_dir == new_dir)
old_dir_mask |= FS_DN_RENAME;
@ -122,7 +122,7 @@ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
mask |= FS_ISDIR;
}
fsnotify(old_dir, old_dir_mask, source, FSNOTIFY_EVENT_INODE, old_name->name,
fsnotify(old_dir, old_dir_mask, source, FSNOTIFY_EVENT_INODE, old_name,
fs_cookie);
fsnotify(new_dir, new_dir_mask, source, FSNOTIFY_EVENT_INODE, new_name,
fs_cookie);
@ -178,7 +178,7 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
take_dentry_name_snapshot(&name, dentry);
fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
name.name.name, 0);
&name.name, 0);
release_dentry_name_snapshot(&name);
dput(parent);
@ -218,7 +218,7 @@ static inline void fsnotify_link(struct inode *dir, struct inode *inode, struct
fsnotify_link_count(inode);
audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE, new_dentry->d_name.name, 0);
fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE, &new_dentry->d_name, 0);
}
/*

4
include/linux/fsnotify_backend.h
View File

@ -350,7 +350,7 @@ struct fsnotify_mark {
/* main fsnotify call to send events */
extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
const unsigned char *name, u32 cookie);
const struct qstr *name, u32 cookie);
extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
extern void __fsnotify_inode_delete(struct inode *inode);
extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
@ -505,7 +505,7 @@ static inline void fsnotify_init_event(struct fsnotify_event *event,
#else
static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
const unsigned char *name, u32 cookie)
const struct qstr *name, u32 cookie)
{
return 0;
}