fuse: don't need GETATTR after every READ

Miklos Szeredi · Miklos Szeredi · commit 802dc0497be2 · 2018-10-15T15:43:06.000+02:00
If 'auto_inval_data' mode is active, then fuse_file_read_iter() will call
fuse_update_attributes(), which will check the attribute validity and send
a GETATTR request if some of the attributes are no longer valid.  The page
cache is then invalidated if the size or mtime have changed.

Then, if a READ request was sent and reply received (which is the case if
the data wasn't cached yet, or if the file is opened for O_DIRECT), the
atime attribute is invalidated.

This will result in the next read() also triggering a GETATTR, ...

This can be fixed by only sending GETATTR if the mode or size are invalid,
we don't need to do a refresh if only atime is invalid.

More generally, none of the callers of fuse_update_attributes() need an
up-to-date atime value, so for now just remove STATX_ATIME from the request
mask when attributes are updated for internal use.

Signed-off-by: Miklos Szeredi &lt;mszeredi@redhat.com&gt;
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
@@ -952,7 +952,9 @@ static int fuse_update_get_attr(struct inode *inode, struct file *file,
 
 int fuse_update_attributes(struct inode *inode, struct file *file)
 {
-	return fuse_update_get_attr(inode, file, NULL, STATX_BASIC_STATS, 0);
+	/* Do *not* need to get atime for internal purposes */
+	return fuse_update_get_attr(inode, file, NULL,
+				    STATX_BASIC_STATS & ~STATX_ATIME, 0);
 }
 
 int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,

Original file line number	Diff line number	Diff line change
`@@ -952,7 +952,9 @@ static int fuse_update_get_attr(struct inode inode, struct file file,`
`952`	`952`
`953`	`953`	`int fuse_update_attributes(struct inode inode, struct file file)`
`954`	`954`	`{`
`955`		`- return fuse_update_get_attr(inode, file, NULL, STATX_BASIC_STATS, 0);`
	`955`	`+ /* Do not need to get atime for internal purposes */`
	`956`	`+ return fuse_update_get_attr(inode, file, NULL,`
	`957`	`+ STATX_BASIC_STATS & ~STATX_ATIME, 0);`
`956`	`958`	`}`
`957`	`959`
`958`	`960`	`int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,`