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@xxxxxx>
---
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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