| Message ID | 20210804160612.3575505-11-krisman@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | File system wide monitoring | expand |
On Wed 04-08-21 12:05:59, Gabriel Krisman Bertazi wrote: > Some file system events (i.e. FS_ERROR) might not be associated with an > inode. For these, it makes sense to associate them directly with the > super block of the file system they apply to. This patch allows the > event to be reported directly against the super block instead of an > inode. > > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> There's a comment before fsnotify() declaration that states that 'either @dir or @inode must be non-NULL' - in this patch it would be good time to update that comment. > @@ -459,12 +460,13 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info) > * if both are non-NULL event may be reported to both. > * @cookie: inotify rename cookie > */ > -int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, > - const struct qstr *file_name, struct inode *inode, u32 cookie) > +int fsnotify(__u32 mask, const void *data, int data_type, > + struct super_block *sb, struct inode *dir, > + const struct qstr *file_name, struct inode *inode, > + u32 cookie) > { Two notes as ideas for consideration: 1) We could derive 'sb' from 'data'. I.e., have a helper like fsnotify_data_sb(data, data_type). For FSNOTIFY_EVENT_PATH and FSNOTIFY_EVENT_INODE this is easy to provide, for FSNOTIFY_EVENT_ERROR we would have to add sb pointer to the structure but I guess that's easy. That way we'd avoid the mostly NULL 'sb' argument. What do you guys think? 2) AFAICS 'inode' can be always derived from 'data' as well. So maybe we can drop it Amir? That being said I can live with the code as is in this patch as well (although with a bit of "ugh, irk ;)" so I want to discuss these ideas). Honza > const struct path *path = fsnotify_data_path(data, data_type); > struct fsnotify_iter_info iter_info = {}; > - struct super_block *sb; > struct mount *mnt = NULL; > struct inode *parent = NULL; > int ret = 0; > @@ -483,7 +485,9 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, > */ > parent = dir; > } > - sb = inode->i_sb; > + > + if (!sb) > + sb = inode->i_sb; > > /* > * Optimization: srcu_read_lock() has a memory barrier which can > diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h > index f8acddcf54fb..39c9dbc46d36 100644 > --- a/include/linux/fsnotify.h > +++ b/include/linux/fsnotify.h > @@ -30,7 +30,8 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask, > struct inode *child, > const struct qstr *name, u32 cookie) > { > - fsnotify(mask, child, FSNOTIFY_EVENT_INODE, dir, name, NULL, cookie); > + fsnotify(mask, child, FSNOTIFY_EVENT_INODE, NULL, dir, name, NULL, > + cookie); > } > > static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry, > @@ -44,7 +45,8 @@ static inline void fsnotify_inode(struct inode *inode, __u32 mask) > if (S_ISDIR(inode->i_mode)) > mask |= FS_ISDIR; > > - fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0); > + fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, NULL, inode, > + 0); > } > > /* Notify this dentry's parent about a child's events. */ > @@ -68,7 +70,7 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask, > return __fsnotify_parent(dentry, mask, data, data_type); > > notify_child: > - return fsnotify(mask, data, data_type, NULL, NULL, inode, 0); > + return fsnotify(mask, data, data_type, NULL, NULL, NULL, inode, 0); > } > > /* > diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h > index 693fe4cb48cf..4a765edd3b2a 100644 > --- a/include/linux/fsnotify_backend.h > +++ b/include/linux/fsnotify_backend.h > @@ -423,8 +423,9 @@ struct fsnotify_mark { > > /* main fsnotify call to send events */ > extern int fsnotify(__u32 mask, const void *data, int data_type, > - struct inode *dir, const struct qstr *name, > - struct inode *inode, u32 cookie); > + struct super_block *sb, struct inode *dir, > + const struct qstr *name, struct inode *inode, > + 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); > @@ -618,8 +619,9 @@ static inline void fsnotify_init_event(struct fsnotify_event *event) > #else > > static inline int fsnotify(__u32 mask, const void *data, int data_type, > - struct inode *dir, const struct qstr *name, > - struct inode *inode, u32 cookie) > + struct super_block *sb, struct inode *dir, > + const struct qstr *name, struct inode *inode, > + u32 cookie) > { > return 0; > } > -- > 2.32.0 >
On Thu, Aug 5, 2021 at 1:24 PM Jan Kara <jack@suse.cz> wrote: > > On Wed 04-08-21 12:05:59, Gabriel Krisman Bertazi wrote: > > Some file system events (i.e. FS_ERROR) might not be associated with an > > inode. For these, it makes sense to associate them directly with the > > super block of the file system they apply to. This patch allows the > > event to be reported directly against the super block instead of an > > inode. > > > > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> > > There's a comment before fsnotify() declaration that states that 'either > @dir or @inode must be non-NULL' - in this patch it would be good time to > update that comment. > > > @@ -459,12 +460,13 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info) > > * if both are non-NULL event may be reported to both. > > * @cookie: inotify rename cookie > > */ > > -int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, > > - const struct qstr *file_name, struct inode *inode, u32 cookie) > > +int fsnotify(__u32 mask, const void *data, int data_type, > > + struct super_block *sb, struct inode *dir, > > + const struct qstr *file_name, struct inode *inode, > > + u32 cookie) > > { > > Two notes as ideas for consideration: > > 1) We could derive 'sb' from 'data'. I.e., have a helper like > fsnotify_data_sb(data, data_type). For FSNOTIFY_EVENT_PATH and > FSNOTIFY_EVENT_INODE this is easy to provide, for FSNOTIFY_EVENT_ERROR we > would have to add sb pointer to the structure but I guess that's easy. That > way we'd avoid the mostly NULL 'sb' argument. What do you guys think? I think that's a great and simple idea that escaped me. > > 2) AFAICS 'inode' can be always derived from 'data' as well. So maybe we > can drop it Amir? If only we could. The reason that we pass the allegedly redundant inode argument is because there are two different distinguished inode arguments: 1. The inode event happened on, which can be referenced from data 2. Inode that may be marked, which is passed in the inode argument Particularly, dirent events carry the inode of the child as data, but intentionally pass NULL inode arguments, because mark on inode itself should not be getting e.g. FAN_DELETE event, but audit_mark_handle_event() uses the child inode data. If we wanted to, we could pass report_mask arg to fsnotify() instead of inode arg and then fsnotify() will build iter_info accordingly, but that sounds very complicated and doesn't gain much. There could be a simpler solution that I am missing... Thanks, Amir.
On Thu 05-08-21 17:14:26, Amir Goldstein wrote: > > 2) AFAICS 'inode' can be always derived from 'data' as well. So maybe we > > can drop it Amir? > > If only we could. The reason that we pass the allegedly redundant inode > argument is because there are two different distinguished inode > arguments: > > 1. The inode event happened on, which can be referenced from data > 2. Inode that may be marked, which is passed in the inode argument > > Particularly, dirent events carry the inode of the child as data, but > intentionally pass NULL inode arguments, because mark on inode > itself should not be getting e.g. FAN_DELETE event, but > audit_mark_handle_event() uses the child inode data. I see, thanks for explanation. I forgot that NULL 'inode' argument from fsnotify_name() is actually needed for this to work. > If we wanted to, we could pass report_mask arg to fsnotify() > instead of inode arg and then fsnotify() will build iter_info > accordingly, but that sounds very complicated and doesn't gain > much. Yeah. I'll think a bit more if we could simplify this but now I don't see anything obvious. Honza
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index c75719312147..eaa0de3a6520 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -883,9 +883,9 @@ static void kernfs_notify_workfn(struct work_struct *work) if (parent) { p_inode = ilookup(info->sb, kernfs_ino(parent)); if (p_inode) { - fsnotify(FS_MODIFY | FS_EVENT_ON_CHILD, - inode, FSNOTIFY_EVENT_INODE, - p_inode, &name, inode, 0); + fsnotify(FS_MODIFY | FS_EVENT_ON_CHILD, inode, + FSNOTIFY_EVENT_INODE, NULL, p_inode, + &name, inode, 0); iput(p_inode); } diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 30d422b8c0fc..36045d5f9d41 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -229,7 +229,8 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data, } notify: - ret = fsnotify(mask, data, data_type, p_inode, file_name, inode, 0); + ret = fsnotify(mask, data, data_type, NULL, p_inode, file_name, + inode, 0); if (file_name) release_dentry_name_snapshot(&name); @@ -459,12 +460,13 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info) * if both are non-NULL event may be reported to both. * @cookie: inotify rename cookie */ -int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, - const struct qstr *file_name, struct inode *inode, u32 cookie) +int fsnotify(__u32 mask, const void *data, int data_type, + struct super_block *sb, struct inode *dir, + const struct qstr *file_name, struct inode *inode, + u32 cookie) { const struct path *path = fsnotify_data_path(data, data_type); struct fsnotify_iter_info iter_info = {}; - struct super_block *sb; struct mount *mnt = NULL; struct inode *parent = NULL; int ret = 0; @@ -483,7 +485,9 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, */ parent = dir; } - sb = inode->i_sb; + + if (!sb) + sb = inode->i_sb; /* * Optimization: srcu_read_lock() has a memory barrier which can diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index f8acddcf54fb..39c9dbc46d36 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -30,7 +30,8 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask, struct inode *child, const struct qstr *name, u32 cookie) { - fsnotify(mask, child, FSNOTIFY_EVENT_INODE, dir, name, NULL, cookie); + fsnotify(mask, child, FSNOTIFY_EVENT_INODE, NULL, dir, name, NULL, + cookie); } static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry, @@ -44,7 +45,8 @@ static inline void fsnotify_inode(struct inode *inode, __u32 mask) if (S_ISDIR(inode->i_mode)) mask |= FS_ISDIR; - fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0); + fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, NULL, inode, + 0); } /* Notify this dentry's parent about a child's events. */ @@ -68,7 +70,7 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask, return __fsnotify_parent(dentry, mask, data, data_type); notify_child: - return fsnotify(mask, data, data_type, NULL, NULL, inode, 0); + return fsnotify(mask, data, data_type, NULL, NULL, NULL, inode, 0); } /* diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 693fe4cb48cf..4a765edd3b2a 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -423,8 +423,9 @@ struct fsnotify_mark { /* main fsnotify call to send events */ extern int fsnotify(__u32 mask, const void *data, int data_type, - struct inode *dir, const struct qstr *name, - struct inode *inode, u32 cookie); + struct super_block *sb, struct inode *dir, + const struct qstr *name, struct inode *inode, + 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); @@ -618,8 +619,9 @@ static inline void fsnotify_init_event(struct fsnotify_event *event) #else static inline int fsnotify(__u32 mask, const void *data, int data_type, - struct inode *dir, const struct qstr *name, - struct inode *inode, u32 cookie) + struct super_block *sb, struct inode *dir, + const struct qstr *name, struct inode *inode, + u32 cookie) { return 0; }
Some file system events (i.e. FS_ERROR) might not be associated with an inode. For these, it makes sense to associate them directly with the super block of the file system they apply to. This patch allows the event to be reported directly against the super block instead of an inode. Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> --- fs/kernfs/file.c | 6 +++--- fs/notify/fsnotify.c | 14 +++++++++----- include/linux/fsnotify.h | 8 +++++--- include/linux/fsnotify_backend.h | 10 ++++++---- 4 files changed, 23 insertions(+), 15 deletions(-)