Messages in this thread | | | Date | Mon, 06 Oct 2014 22:09:12 +0200 | From | Heinrich Schuchardt <> | Subject | Re: [PATCH 1/1] ftruncate: create FAN_MODIFY and IN_MODIFY events |
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On 06.10.2014 15:24, Jan Kara wrote: > On Fri 03-10-14 20:16:30, Heinrich Schuchardt wrote: >> The fanotify and the inotify API can be used to monitor changes of the file >> system. >> >> System call ftruncate modifies files. Hence it should trigger the corresponding >> fanotify (FAN_MODIFY) and inotify (IN_MODIFY) events. > Hum, I would think that the appropriate event gets generated by > fsnotify_change() called from notify_change()? > > Honza
Hello Jan,
thank you for reviewing.
fsnotify_change() calls fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
fsnotify_modify() calls fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
Only with FSNOTIFY_EVENT_PATH a mount is determined in fsnotify().
So a FAN_MODIFY event for a mount cannot occur. But I also did not see a FAN_MODIFY event when watching a file either.
IN_MODIFY events are actually created.
So would it be better to do the change in do_truncate and replace the call to notify_change by a call to fsnotify_modify?
I just had a look at http://lxr.free-electrons.com/ident?i=notify_change
There seem to be some other usages of notify_change that deserve consideration, e.g. in ecryptfs_truncate().
Best regards
Heinrich Schuchardt
>> >> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> >> --- >> fs/open.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/fs/open.c b/fs/open.c >> index d6fd3ac..e36f26e 100644 >> --- a/fs/open.c >> +++ b/fs/open.c >> @@ -189,6 +189,8 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) >> error = security_path_truncate(&f.file->f_path); >> if (!error) >> error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file); >> + if (!error) >> + fsnotify_modify(f.file); >> sb_end_write(inode->i_sb); >> out_putf: >> fdput(f); >> -- >> 2.1.0 >>
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