Messages in this thread | | | Date | Fri, 7 Apr 2006 10:30:02 -0400 | From | Amy Griffis <> | Subject | Re: [RFC][PATCH] inotify kernel api |
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On Thu, Apr 06, 2006 at 01:06:01PM -0400, Amy Griffis wrote: > The following patch against 2.6.17-rc1-mm1 introduces a kernel API > for inotify.
I realized that my first email assumed quite a bit of knowledge about inotify. Here is a description of the interface I'm proposing.
Each inotify instance is represented by an inotify_handle structure. For the inotify consumer supplying support to userspace, each inotify_device has an associated inotify_handle.
Each inotify watch is represented by an inotify_watch structure. Watches are chained off of each associated inode and inotify_handle.
Using the Inotify Kernel Interface ---------------------------------- First you must initialize an inotify instance.
struct inotify_handle *ih = inotify_init(my_event_handler);
You are given an opaque inotify_handle, which you use for any further calls to inotify. You provide a function to be called to process events on your registered watches.
void my_event_handle(struct inotify_watch *iwatch, u32 wd, u32 mask, u32 cookie, const char *name, struct inode *inode)
iwatch - the pointer to the inotify_watch that triggered this call wd - the watch descriptor mask - describes the event that occurred cookie - an identifier for synchronizing events name - the dentry name for affected files in a directory-based event inode - the affected inode in a directory-based event
You may add watches by providing a pre-allocated inotify_watch structure and specifying the inode to watch along with an inotify event mask. You must pin the inode during the call. You will likely wish to embed the inotify_watch structure in a structure of your own which contains other information about the watch.
s32 wd = inotify_add_watch(ih, &my_watch->iwatch, inode, mask);
You may use the watch descriptor (wd) or the address of the inotify_watch for other inotify operations. You must not directly read or manipulate data in the inotify_watch. Additionally, you must not call inotify_add_watch() more than once for a given inotify_watch structure, unless you have first called either inotify_rm_watch() or inotify_rm_wd().
To determine if you have already registered a watch for a given inode, you may call inotify_find_watch(), which gives you both the wd and the watch pointer for the inotify_watch, or an error if the watch does not exist.
wd = inotify_find_watch(ih, inode, &watchp);
You may use container_of() on the watch pointer to access your own data associated with a given watch.
Call inotify_find_update_watch() to update the event mask for an existing watch. inotify_find_update_watch() returns the wd of the updated watch, or an error if the watch does not exist.
wd = inotify_find_update_watch(ih, inode, mask);
An existing watch may be removed by calling either inotify_rm_watch() or inotify_rm_wd().
int ret = inotify_rm_watch(ih, &my_watch->iwatch); int ret = inotify_rm_wd(ih, wd);
Call inotify_destroy() to remove all watches from your inotify instance and release it.
inotify_destroy(ih);
When inotify removes a watch, it sends an IN_IGNORED event to your callback. You may use this event as an indication to free the watch memory. Note that inotify may remove a watch due to filesystem events, as well as by your request.
Function Prototypes ------------------- struct inotify_handle *inotify_init(void (*cb)(struct inotify_watch *, u32, u32, u32, const char *, struct inode *))
s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch, struct inode *inode, u32 mask)
s32 inotify_find_watch(struct inotify_handle *ih, struct inode *inode, struct inotify_watch **watchp)
s32 inotify_find_update_watch(struct inotify_handle *ih, struct inode *inode, u32 mask)
int inotify_rm_wd(struct inotify_handle *ih, u32 wd)
int inotify_rm_watch(struct inotify_handle *ih, struct inotify_watch *watch)
void inotify_destroy(struct inotify_handle *ih) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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