fs: clarify rate limit suppressed buffer I/O errors

When quiet_error applies rate limiting to buffer_io_error calls, what the
they apply to is unclear because the name is so generic, particularly
if the messages are interleaved with others:

[ 1936.063572] quiet_error: 664293 callbacks suppressed
[ 1936.065297] Buffer I/O error on dev sdr, logical block 257429952, lost async page write
[ 1936.067814] Buffer I/O error on dev sdr, logical block 257429953, lost async page write

Also, the function uses printk_ratelimit(), although printk.h includes a
comment advising "Please don't use... Instead use printk_ratelimited()."

Change buffer_io_error to check the BH_Quiet bit itself, drop the
printk_ratelimit call, and print using printk_ratelimited.

This makes the messages look like:

[ 387.208839] buffer_io_error: 676394 callbacks suppressed
[ 387.210693] Buffer I/O error on dev sdr, logical block 211291776, lost async page write
[ 387.213432] Buffer I/O error on dev sdr, logical block 211291777, lost async page write

Signed-off-by: Robert Elliott <[e-mail]>
Reviewed-by: Webb Scales <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

fs/buffer.c

···
 	page_cache_release(page);
 }
 
-
-static int quiet_error(struct buffer_head *bh)
-{
-	if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
-		return 0;
-	return 1;
-}
-
-
 static void buffer_io_error(struct buffer_head *bh, char *msg)
 {
 	char b[BDEVNAME_SIZE];
-	printk(KERN_ERR "Buffer I/O error on dev %s, logical block %llu%s\n",
+
+	if (!test_bit(BH_Quiet, &bh->b_state))
+		printk_ratelimited(KERN_ERR
+			"Buffer I/O error on dev %s, logical block %llu%s\n",
 			bdevname(bh->b_bdev, b),
 			(unsigned long long)bh->b_blocknr, msg);
 }
···
 	if (uptodate) {
 		set_buffer_uptodate(bh);
 	} else {
-		if (!quiet_error(bh))
-			buffer_io_error(bh, ", lost sync page write");
+		buffer_io_error(bh, ", lost sync page write");
 		set_buffer_write_io_error(bh);
 		clear_buffer_uptodate(bh);
 	}
···
 		set_buffer_uptodate(bh);
 	} else {
 		clear_buffer_uptodate(bh);
-		if (!quiet_error(bh))
-			buffer_io_error(bh, ", async page read");
+		buffer_io_error(bh, ", async page read");
 		SetPageError(page);
 	}
 
···
 	if (uptodate) {
 		set_buffer_uptodate(bh);
 	} else {
-		if (!quiet_error(bh))
-			buffer_io_error(bh, ", lost async page write");
+		buffer_io_error(bh, ", lost async page write");
 		set_bit(AS_EIO, &page->mapping->flags);
 		set_buffer_write_io_error(bh);
 		clear_buffer_uptodate(bh);