Commit 9740d171 authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fsnotify: pass optional file access range in pre-content event 



We would like to add file range information to pre-content events.

Pass a struct file_range with offset and length to event handler
along with pre-content permission event.

The offset and length are aligned to page size, but we may need to
align them to minimum folio size for filesystems with large block size.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Link: https://patch.msgid.link/88eddee301231d814aede27fb4d5b41ae37c9702.1731684329.git.josef@toxicpanda.com
parent f156524e

fs/notify/fanotify/fanotify.c

+9 −2
Original line number Diff line number Diff line
@@ -548,9 +548,13 @@ static struct fanotify_event *fanotify_alloc_path_event(const struct path *path, 
	return &pevent->fae;

}



static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path,

static struct fanotify_event *fanotify_alloc_perm_event(const void *data,

							int data_type,

							gfp_t gfp)

{

	const struct path *path = fsnotify_data_path(data, data_type);

	const struct file_range *range =

			    fsnotify_data_file_range(data, data_type);

	struct fanotify_perm_event *pevent;



	pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
@@ -564,6 +568,9 @@ static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path, 
	pevent->hdr.len = 0;

	pevent->state = FAN_EVENT_INIT;

	pevent->path = *path;

	/* NULL ppos means no range info */

	pevent->ppos = range ? &range->pos : NULL;

	pevent->count = range ? range->count : 0;

	path_get(path);



	return &pevent->fae;
@@ -801,7 +808,7 @@ static struct fanotify_event *fanotify_alloc_event( 
	old_memcg = set_active_memcg(group->memcg);



	if (fanotify_is_perm_event(mask)) {

		event = fanotify_alloc_perm_event(path, gfp);

		event = fanotify_alloc_perm_event(data, data_type, gfp);

	} else if (fanotify_is_error_event(mask)) {

		event = fanotify_alloc_error_event(group, fsid, data,

						   data_type, &hash);

fs/notify/fanotify/fanotify.h

+2 −0
Original line number Diff line number Diff line
@@ -425,6 +425,8 @@ FANOTIFY_PE(struct fanotify_event *event) 
struct fanotify_perm_event {

	struct fanotify_event fae;

	struct path path;

	const loff_t *ppos;		/* optional file range info */

	size_t count;

	u32 response;			/* userspace answer to the event */

	unsigned short state;		/* state of the event */

	int fd;		/* fd we passed to userspace for this event */

fs/notify/fsnotify.c

+18 −0
Original line number Diff line number Diff line
@@ -203,6 +203,24 @@ static inline bool fsnotify_object_watched(struct inode *inode, __u32 mnt_mask, 
	return mask & marks_mask & ALL_FSNOTIFY_EVENTS;

}



/* Report pre-content event with optional range info */

int fsnotify_pre_content(const struct path *path, const loff_t *ppos,

			 size_t count)

{

	struct file_range range;



	/* Report page aligned range only when pos is known */

	if (!ppos)

		return fsnotify_path(path, FS_PRE_ACCESS);



	range.path = path;

	range.pos = PAGE_ALIGN_DOWN(*ppos);

	range.count = PAGE_ALIGN(*ppos + count) - range.pos;



	return fsnotify_parent(path->dentry, FS_PRE_ACCESS, &range,

			       FSNOTIFY_EVENT_FILE_RANGE);

}



/*

 * Notify this dentry's parent about a child's events with child name info

 * if parent is watching or if inode/sb/mount are interested in events with

include/linux/fsnotify.h

+2 −2
Original line number Diff line number Diff line
@@ -154,7 +154,7 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, 
	 * read()/write() and other types of access generate pre-content events.

	 */

	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) {

		int ret = fsnotify_path(&file->f_path, FS_PRE_ACCESS);

		int ret = fsnotify_pre_content(&file->f_path, ppos, count);



		if (ret)

			return ret;
@@ -171,7 +171,7 @@ static inline int fsnotify_file_area_perm(struct file *file, int perm_mask, 
}



/*

 * fsnotify_file_perm - permission hook before file access

 * fsnotify_file_perm - permission hook before file access (unknown range)

 */

static inline int fsnotify_file_perm(struct file *file, int perm_mask)

{

include/linux/fsnotify_backend.h

+40 −0
Original line number Diff line number Diff line
@@ -294,6 +294,7 @@ static inline void fsnotify_group_assert_locked(struct fsnotify_group *group) 
/* When calling fsnotify tell it if the data is a path or inode */

enum fsnotify_data_type {

	FSNOTIFY_EVENT_NONE,

	FSNOTIFY_EVENT_FILE_RANGE,

	FSNOTIFY_EVENT_PATH,

	FSNOTIFY_EVENT_INODE,

	FSNOTIFY_EVENT_DENTRY,
@@ -306,6 +307,17 @@ struct fs_error_report { 
	struct super_block *sb;

};



struct file_range {

	const struct path *path;

	loff_t pos;

	size_t count;

};



static inline const struct path *file_range_path(const struct file_range *range)

{

	return range->path;

}



static inline struct inode *fsnotify_data_inode(const void *data, int data_type)

{

	switch (data_type) {
@@ -315,6 +327,8 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type) 
		return d_inode(data);

	case FSNOTIFY_EVENT_PATH:

		return d_inode(((const struct path *)data)->dentry);

	case FSNOTIFY_EVENT_FILE_RANGE:

		return d_inode(file_range_path(data)->dentry);

	case FSNOTIFY_EVENT_ERROR:

		return ((struct fs_error_report *)data)->inode;

	default:
@@ -330,6 +344,8 @@ static inline struct dentry *fsnotify_data_dentry(const void *data, int data_typ 
		return (struct dentry *)data;

	case FSNOTIFY_EVENT_PATH:

		return ((const struct path *)data)->dentry;

	case FSNOTIFY_EVENT_FILE_RANGE:

		return file_range_path(data)->dentry;

	default:

		return NULL;

	}
@@ -341,6 +357,8 @@ static inline const struct path *fsnotify_data_path(const void *data, 
	switch (data_type) {

	case FSNOTIFY_EVENT_PATH:

		return data;

	case FSNOTIFY_EVENT_FILE_RANGE:

		return file_range_path(data);

	default:

		return NULL;

	}
@@ -356,6 +374,8 @@ static inline struct super_block *fsnotify_data_sb(const void *data, 
		return ((struct dentry *)data)->d_sb;

	case FSNOTIFY_EVENT_PATH:

		return ((const struct path *)data)->dentry->d_sb;

	case FSNOTIFY_EVENT_FILE_RANGE:

		return file_range_path(data)->dentry->d_sb;

	case FSNOTIFY_EVENT_ERROR:

		return ((struct fs_error_report *) data)->sb;

	default:
@@ -375,6 +395,18 @@ static inline struct fs_error_report *fsnotify_data_error_report( 
	}

}



static inline const struct file_range *fsnotify_data_file_range(

							const void *data,

							int data_type)

{

	switch (data_type) {

	case FSNOTIFY_EVENT_FILE_RANGE:

		return (struct file_range *)data;

	default:

		return NULL;

	}

}



/*

 * Index to merged marks iterator array that correlates to a type of watch.

 * The type of watched object can be deduced from the iterator type, but not
@@ -863,9 +895,17 @@ static inline void fsnotify_init_event(struct fsnotify_event *event) 
{

	INIT_LIST_HEAD(&event->list);

}

int fsnotify_pre_content(const struct path *path, const loff_t *ppos,

			 size_t count);



#else



static inline int fsnotify_pre_content(const struct path *path,

				       const loff_t *ppos, size_t count)

{

	return 0;

}



static inline int fsnotify(__u32 mask, const void *data, int data_type,

			   struct inode *dir, const struct qstr *name,

			   struct inode *inode, u32 cookie)