From 6473ea760ca1707ade74de5b57e74189d14f8e10 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:09 +0200 Subject: fsnotify: tidy up FS_ and FAN_ constants Order by value, so the free value ranges are easier to find. Link: https://lore.kernel.org/r/20200319151022.31456-2-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify_backend.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 1915bdba2fad..db3cabb4600e 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -49,16 +49,15 @@ #define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */ #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ -#define FS_ISDIR 0x40000000 /* event occurred against dir */ -#define FS_IN_ONESHOT 0x80000000 /* only send event once */ - -#define FS_DN_RENAME 0x10000000 /* file renamed */ -#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ - /* This inode cares about things that happen to its children. Always set for * dnotify and inotify. */ #define FS_EVENT_ON_CHILD 0x08000000 +#define FS_DN_RENAME 0x10000000 /* file renamed */ +#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ +#define FS_ISDIR 0x40000000 /* event occurred against dir */ +#define FS_IN_ONESHOT 0x80000000 /* only send event once */ + #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) /* -- cgit v1.2.3 From eae36a2b8324c9dd0a66b2ae32abd4a456e49c39 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:10 +0200 Subject: fsnotify: factor helpers fsnotify_dentry() and fsnotify_file() Most of the code in fsnotify hooks is boiler plate of one or the other. Link: https://lore.kernel.org/r/20200319151022.31456-3-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify.h | 99 ++++++++++++++++++------------------------------ 1 file changed, 37 insertions(+), 62 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index a2d5d175d3c1..f54936aa0365 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -41,16 +41,36 @@ static inline int fsnotify_parent(const struct path *path, } /* - * Simple wrapper to consolidate calls fsnotify_parent()/fsnotify() when - * an event is on a path. + * Simple wrappers to consolidate calls fsnotify_parent()/fsnotify() when + * an event is on a file/dentry. */ -static inline int fsnotify_path(struct inode *inode, const struct path *path, - __u32 mask) +static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask) { - int ret = fsnotify_parent(path, NULL, mask); + struct inode *inode = d_inode(dentry); + if (S_ISDIR(inode->i_mode)) + mask |= FS_ISDIR; + + fsnotify_parent(NULL, dentry, mask); + fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0); +} + +static inline int fsnotify_file(struct file *file, __u32 mask) +{ + const struct path *path = &file->f_path; + struct inode *inode = file_inode(file); + int ret; + + if (file->f_mode & FMODE_NONOTIFY) + return 0; + + if (S_ISDIR(inode->i_mode)) + mask |= FS_ISDIR; + + ret = fsnotify_parent(path, NULL, mask); if (ret) return ret; + return fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0); } @@ -58,19 +78,16 @@ static inline int fsnotify_path(struct inode *inode, const struct path *path, static inline int fsnotify_perm(struct file *file, int mask) { int ret; - const struct path *path = &file->f_path; - struct inode *inode = file_inode(file); __u32 fsnotify_mask = 0; - if (file->f_mode & FMODE_NONOTIFY) - return 0; if (!(mask & (MAY_READ | MAY_OPEN))) return 0; + if (mask & MAY_OPEN) { fsnotify_mask = FS_OPEN_PERM; if (file->f_flags & __FMODE_EXEC) { - ret = fsnotify_path(inode, path, FS_OPEN_EXEC_PERM); + ret = fsnotify_file(file, FS_OPEN_EXEC_PERM); if (ret) return ret; @@ -79,10 +96,7 @@ static inline int fsnotify_perm(struct file *file, int mask) fsnotify_mask = FS_ACCESS_PERM; } - if (S_ISDIR(inode->i_mode)) - fsnotify_mask |= FS_ISDIR; - - return fsnotify_path(inode, path, fsnotify_mask); + return fsnotify_file(file, fsnotify_mask); } /* @@ -229,15 +243,7 @@ static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry) */ static inline void fsnotify_access(struct file *file) { - const struct path *path = &file->f_path; - struct inode *inode = file_inode(file); - __u32 mask = FS_ACCESS; - - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; - - if (!(file->f_mode & FMODE_NONOTIFY)) - fsnotify_path(inode, path, mask); + fsnotify_file(file, FS_ACCESS); } /* @@ -245,15 +251,7 @@ static inline void fsnotify_access(struct file *file) */ static inline void fsnotify_modify(struct file *file) { - const struct path *path = &file->f_path; - struct inode *inode = file_inode(file); - __u32 mask = FS_MODIFY; - - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; - - if (!(file->f_mode & FMODE_NONOTIFY)) - fsnotify_path(inode, path, mask); + fsnotify_file(file, FS_MODIFY); } /* @@ -261,16 +259,12 @@ static inline void fsnotify_modify(struct file *file) */ static inline void fsnotify_open(struct file *file) { - const struct path *path = &file->f_path; - struct inode *inode = file_inode(file); __u32 mask = FS_OPEN; - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; if (file->f_flags & __FMODE_EXEC) mask |= FS_OPEN_EXEC; - fsnotify_path(inode, path, mask); + fsnotify_file(file, mask); } /* @@ -278,16 +272,10 @@ static inline void fsnotify_open(struct file *file) */ static inline void fsnotify_close(struct file *file) { - const struct path *path = &file->f_path; - struct inode *inode = file_inode(file); - fmode_t mode = file->f_mode; - __u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE; + __u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE : + FS_CLOSE_NOWRITE; - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; - - if (!(file->f_mode & FMODE_NONOTIFY)) - fsnotify_path(inode, path, mask); + fsnotify_file(file, mask); } /* @@ -295,14 +283,7 @@ static inline void fsnotify_close(struct file *file) */ static inline void fsnotify_xattr(struct dentry *dentry) { - struct inode *inode = dentry->d_inode; - __u32 mask = FS_ATTRIB; - - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; - - fsnotify_parent(NULL, dentry, mask); - fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0); + fsnotify_dentry(dentry, FS_ATTRIB); } /* @@ -311,7 +292,6 @@ static inline void fsnotify_xattr(struct dentry *dentry) */ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid) { - struct inode *inode = dentry->d_inode; __u32 mask = 0; if (ia_valid & ATTR_UID) @@ -332,13 +312,8 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid) if (ia_valid & ATTR_MODE) mask |= FS_ATTRIB; - if (mask) { - if (S_ISDIR(inode->i_mode)) - mask |= FS_ISDIR; - - fsnotify_parent(NULL, dentry, mask); - fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0); - } + if (mask) + fsnotify_dentry(dentry, mask); } #endif /* _LINUX_FS_NOTIFY_H */ -- cgit v1.2.3 From a1aae0570a2b806937120921db2c5d3100ca55fc Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:11 +0200 Subject: fsnotify: funnel all dirent events through fsnotify_name() Factor out fsnotify_name() from fsnotify_dirent(), so it can also serve link and rename events and use this helper to report all directory entry change events. Both helpers return void because no caller checks their return value. Link: https://lore.kernel.org/r/20200319151022.31456-4-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify.h | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index f54936aa0365..751da17e003d 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -18,16 +18,24 @@ #include /* - * Notify this @dir inode about a change in the directory entry @dentry. + * Notify this @dir inode about a change in a child directory entry. + * The directory entry may have turned positive or negative or its inode may + * have changed (i.e. renamed over). * * Unlike fsnotify_parent(), the event will be reported regardless of the * FS_EVENT_ON_CHILD mask on the parent inode. */ -static inline int fsnotify_dirent(struct inode *dir, struct dentry *dentry, - __u32 mask) +static inline void fsnotify_name(struct inode *dir, __u32 mask, + struct inode *child, + const struct qstr *name, u32 cookie) { - return fsnotify(dir, mask, d_inode(dentry), FSNOTIFY_EVENT_INODE, - &dentry->d_name, 0); + fsnotify(dir, mask, child, FSNOTIFY_EVENT_INODE, name, cookie); +} + +static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry, + __u32 mask) +{ + fsnotify_name(dir, mask, d_inode(dentry), &dentry->d_name, 0); } /* Notify this dentry's parent about a child's events. */ @@ -136,10 +144,8 @@ 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, - fs_cookie); - fsnotify(new_dir, new_dir_mask, source, FSNOTIFY_EVENT_INODE, new_name, - fs_cookie); + fsnotify_name(old_dir, old_dir_mask, source, old_name, fs_cookie); + fsnotify_name(new_dir, new_dir_mask, source, new_name, fs_cookie); if (target) fsnotify_link_count(target); @@ -194,12 +200,13 @@ static inline void fsnotify_create(struct inode *inode, struct dentry *dentry) * Note: We have to pass also the linked inode ptr as some filesystems leave * new_dentry->d_inode NULL and instantiate inode pointer later */ -static inline void fsnotify_link(struct inode *dir, struct inode *inode, struct dentry *new_dentry) +static inline void fsnotify_link(struct inode *dir, struct inode *inode, + struct dentry *new_dentry) { 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, 0); + fsnotify_name(dir, FS_CREATE, inode, &new_dentry->d_name, 0); } /* -- cgit v1.2.3 From aa93bdc5500cc93ba31afeda1a61610d117947ad Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:12 +0200 Subject: fsnotify: use helpers to access data by data_type Create helpers to access path and inode from different data types. Link: https://lore.kernel.org/r/20200319151022.31456-5-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify_backend.h | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index db3cabb4600e..5cc838db422a 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -212,10 +212,36 @@ struct fsnotify_group { }; }; -/* 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_INODE 2 +/* When calling fsnotify tell it if the data is a path or inode */ +enum fsnotify_data_type { + FSNOTIFY_EVENT_NONE, + FSNOTIFY_EVENT_PATH, + FSNOTIFY_EVENT_INODE, +}; + +static inline const struct inode *fsnotify_data_inode(const void *data, + int data_type) +{ + switch (data_type) { + case FSNOTIFY_EVENT_INODE: + return data; + case FSNOTIFY_EVENT_PATH: + return d_inode(((const struct path *)data)->dentry); + default: + return NULL; + } +} + +static inline const struct path *fsnotify_data_path(const void *data, + int data_type) +{ + switch (data_type) { + case FSNOTIFY_EVENT_PATH: + return data; + default: + return NULL; + } +} enum fsnotify_obj_type { FSNOTIFY_OBJ_TYPE_INODE, -- cgit v1.2.3 From 017de65fe58f2b0ca428b5830609520ded5898b9 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:13 +0200 Subject: fsnotify: simplify arguments passing to fsnotify_parent() Instead of passing both dentry and path and having to figure out which one to use, pass data/data_type to simplify the code. Link: https://lore.kernel.org/r/20200319151022.31456-6-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify.h | 14 ++------------ include/linux/fsnotify_backend.h | 14 ++++++++------ 2 files changed, 10 insertions(+), 18 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index 751da17e003d..860018f3e545 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -38,16 +38,6 @@ static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry, fsnotify_name(dir, mask, d_inode(dentry), &dentry->d_name, 0); } -/* Notify this dentry's parent about a child's events. */ -static inline int fsnotify_parent(const struct path *path, - struct dentry *dentry, __u32 mask) -{ - if (!dentry) - dentry = path->dentry; - - return __fsnotify_parent(path, dentry, mask); -} - /* * Simple wrappers to consolidate calls fsnotify_parent()/fsnotify() when * an event is on a file/dentry. @@ -59,7 +49,7 @@ static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask) if (S_ISDIR(inode->i_mode)) mask |= FS_ISDIR; - fsnotify_parent(NULL, dentry, mask); + fsnotify_parent(dentry, mask, inode, FSNOTIFY_EVENT_INODE); fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0); } @@ -75,7 +65,7 @@ static inline int fsnotify_file(struct file *file, __u32 mask) if (S_ISDIR(inode->i_mode)) mask |= FS_ISDIR; - ret = fsnotify_parent(path, NULL, mask); + ret = fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH); if (ret) return ret; diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 5cc838db422a..337c87cf34d6 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -376,9 +376,10 @@ struct fsnotify_mark { /* called from the vfs helpers */ /* main fsnotify call to send events */ -extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, - const struct qstr *name, u32 cookie); -extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask); +extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, + int data_type, const struct qstr *name, u32 cookie); +extern int fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data, + int data_type); extern void __fsnotify_inode_delete(struct inode *inode); extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); extern void fsnotify_sb_delete(struct super_block *sb); @@ -533,13 +534,14 @@ 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 struct qstr *name, u32 cookie) +static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, + int data_type, const struct qstr *name, u32 cookie) { return 0; } -static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask) +static inline int fsnotify_parent(struct dentry *dentry, __u32 mask, + const void *data, int data_type) { return 0; } -- cgit v1.2.3 From dfc2d2594e4a79204a3967585245f00644b8f838 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:15 +0200 Subject: fsnotify: replace inode pointer with an object id The event inode field is used only for comparison in queue merges and cannot be dereferenced after handle_event(), because it does not hold a refcount on the inode. Replace it with an abstract id to do the same thing. Link: https://lore.kernel.org/r/20200319151022.31456-8-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify_backend.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 337c87cf34d6..c72cbea20ef7 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -132,8 +132,7 @@ struct fsnotify_ops { */ struct fsnotify_event { struct list_head list; - /* inode may ONLY be dereferenced during handle_event(). */ - struct inode *inode; /* either the inode the event happened to or its parent */ + unsigned long objectid; /* identifier for queue merges */ }; /* @@ -526,10 +525,10 @@ extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info); extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info); static inline void fsnotify_init_event(struct fsnotify_event *event, - struct inode *inode) + unsigned long objectid) { INIT_LIST_HEAD(&event->list); - event->inode = inode; + event->objectid = objectid; } #else -- cgit v1.2.3 From 9e2ba2c34f1922ca1e0c7d31b30ace5842c2e7d1 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:19 +0200 Subject: fanotify: send FAN_DIR_MODIFY event flavor with dir inode and name Dirent events are going to be supported in two flavors: 1. Directory fid info + mask that includes the specific event types (e.g. FAN_CREATE) and an optional FAN_ONDIR flag. 2. Directory fid info + name + mask that includes only FAN_DIR_MODIFY. To request the second event flavor, user needs to set the event type FAN_DIR_MODIFY in the mark mask. The first flavor is supported since kernel v5.1 for groups initialized with flag FAN_REPORT_FID. It is intended to be used for watching directories in "batch mode" - the watcher is notified when directory is changed and re-scans the directory content in response. This event flavor is stored more compactly in the event queue, so it is optimal for workloads with frequent directory changes. The second event flavor is intended to be used for watching large directories, where the cost of re-scan of the directory on every change is considered too high. The watcher getting the event with the directory fid and entry name is expected to call fstatat(2) to query the content of the entry after the change. Legacy inotify events are reported with name and event mask (e.g. "foo", FAN_CREATE | FAN_ONDIR). That can lead users to the conclusion that there is *currently* an entry "foo" that is a sub-directory, when in fact "foo" may be negative or non-dir by the time user gets the event. To make it clear that the current state of the named entry is unknown, when reporting an event with name info, fanotify obfuscates the specific event types (e.g. create,delete,rename) and uses a common event type - FAN_DIR_MODIFY to describe the change. This should make it harder for users to make wrong assumptions and write buggy filesystem monitors. At this point, name info reporting is not yet implemented, so trying to set FAN_DIR_MODIFY in mark mask will return -EINVAL. Link: https://lore.kernel.org/r/20200319151022.31456-12-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fsnotify.h | 6 ++++++ include/linux/fsnotify_backend.h | 4 +++- 2 files changed, 9 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index 860018f3e545..5ab28f6c7d26 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -30,6 +30,12 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask, const struct qstr *name, u32 cookie) { fsnotify(dir, mask, child, FSNOTIFY_EVENT_INODE, name, cookie); + /* + * Send another flavor of the event without child inode data and + * without the specific event type (e.g. FS_CREATE|FS_IS_DIR). + * The name is relative to the dir inode the event is reported to. + */ + fsnotify(dir, FS_DIR_MODIFY, dir, FSNOTIFY_EVENT_INODE, name, 0); } static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry, diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index c72cbea20ef7..f0c506405b54 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -47,6 +47,7 @@ #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ #define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */ +#define FS_DIR_MODIFY 0x00080000 /* Directory entry was modified */ #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ /* This inode cares about things that happen to its children. Always set for @@ -66,7 +67,8 @@ * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event * when a directory entry inside a child subdir changes. */ -#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE) +#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | \ + FS_DIR_MODIFY) #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \ FS_OPEN_EXEC_PERM) -- cgit v1.2.3 From 44d705b0370b1d581f46ff23e5d33e8b5ff8ec58 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 19 Mar 2020 17:10:22 +0200 Subject: fanotify: report name info for FAN_DIR_MODIFY event Report event FAN_DIR_MODIFY with name in a variable length record similar to how fid's are reported. With name info reporting implemented, setting FAN_DIR_MODIFY in mark mask is now allowed. When events are reported with name, the reported fid identifies the directory and the name follows the fid. The info record type for this event info is FAN_EVENT_INFO_TYPE_DFID_NAME. For now, all reported events have at most one info record which is either FAN_EVENT_INFO_TYPE_FID or FAN_EVENT_INFO_TYPE_DFID_NAME (for FAN_DIR_MODIFY). Later on, events "on child" will report both records. There are several ways that an application can use this information: 1. When watching a single directory, the name is always relative to the watched directory, so application need to fstatat(2) the name relative to the watched directory. 2. When watching a set of directories, the application could keep a map of dirfd for all watched directories and hash the map by fid obtained with name_to_handle_at(2). When getting a name event, the fid in the event info could be used to lookup the base dirfd in the map and then call fstatat(2) with that dirfd. 3. When watching a filesystem (FAN_MARK_FILESYSTEM) or a large set of directories, the application could use open_by_handle_at(2) with the fid in event info to obtain dirfd for the directory where event happened and call fstatat(2) with this dirfd. The last option scales better for a large number of watched directories. The first two options may be available in the future also for non privileged fanotify watchers, because open_by_handle_at(2) requires the CAP_DAC_READ_SEARCH capability. Link: https://lore.kernel.org/r/20200319151022.31456-15-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/linux/fanotify.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index b79fa9bb7359..3049a6c06d9e 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -47,7 +47,8 @@ * Directory entry modification events - reported only to directory * where entry is modified and not to a watching parent. */ -#define FANOTIFY_DIRENT_EVENTS (FAN_MOVE | FAN_CREATE | FAN_DELETE) +#define FANOTIFY_DIRENT_EVENTS (FAN_MOVE | FAN_CREATE | FAN_DELETE | \ + FAN_DIR_MODIFY) /* Events that can only be reported with data type FSNOTIFY_EVENT_INODE */ #define FANOTIFY_INODE_EVENTS (FANOTIFY_DIRENT_EVENTS | \ -- cgit v1.2.3