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* [PATCH v3] mkfs: Break block discard into chunks of 2 GB
@ 2019-11-28  6:21 Pavel Reichl
  2019-11-30 22:01 ` Chaitanya Kulkarni
  2019-12-09 22:00 ` Eric Sandeen
  0 siblings, 2 replies; 12+ messages in thread
From: Pavel Reichl @ 2019-11-28  6:21 UTC (permalink / raw)
  To: linux-xfs; +Cc: Pavel Reichl

Some users are not happy about the BLKDISCARD taking too long and at the same
time not being informed about that - so they think that the command actually
hung.

This commit changes code so that progress reporting is possible and also typing
the ^C will cancel the ongoing BLKDISCARD.

Signed-off-by: Pavel Reichl <preichl@redhat.com>
---
 mkfs/xfs_mkfs.c | 50 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 18338a61..0defadb2 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -1240,17 +1240,40 @@ done:
 }
 
 static void
-discard_blocks(dev_t dev, uint64_t nsectors)
+discard_blocks(dev_t dev, uint64_t nsectors, int quiet)
 {
-	int fd;
+	int		fd;
+	uint64_t	offset = 0;
+	/* Discard the device 2G at a time */
+	const uint64_t	step = 2ULL << 30;
+	const uint64_t	count = BBTOB(nsectors);
 
-	/*
-	 * We intentionally ignore errors from the discard ioctl.  It is
-	 * not necessary for the mkfs functionality but just an optimization.
-	 */
 	fd = libxfs_device_to_fd(dev);
-	if (fd > 0)
-		platform_discard_blocks(fd, 0, nsectors << 9);
+	if (fd <= 0)
+		return;
+	if (!quiet) {
+		printf("Discarding blocks...\n");
+		printf("...\n");
+	}
+
+	/* The block discarding happens in smaller batches so it can be
+	 * interrupted prematurely
+	 */
+	while (offset < count) {
+		uint64_t	tmp_step = min(step, count - offset);
+
+		/*
+		 * We intentionally ignore errors from the discard ioctl. It is
+		 * not necessary for the mkfs functionality but just an
+		 * optimization. However we should stop on error.
+		 */
+		if (platform_discard_blocks(fd, offset, tmp_step))
+			return;
+
+		offset += tmp_step;
+	}
+	if (!quiet)
+		printf("Done.\n");
 }
 
 static __attribute__((noreturn)) void
@@ -2507,18 +2530,19 @@ open_devices(
 
 static void
 discard_devices(
-	struct libxfs_xinit	*xi)
+	struct libxfs_xinit	*xi,
+	int			quiet)
 {
 	/*
 	 * This function has to be called after libxfs has been initialized.
 	 */
 
 	if (!xi->disfile)
-		discard_blocks(xi->ddev, xi->dsize);
+		discard_blocks(xi->ddev, xi->dsize, quiet);
 	if (xi->rtdev && !xi->risfile)
-		discard_blocks(xi->rtdev, xi->rtsize);
+		discard_blocks(xi->rtdev, xi->rtsize, quiet);
 	if (xi->logdev && xi->logdev != xi->ddev && !xi->lisfile)
-		discard_blocks(xi->logdev, xi->logBBsize);
+		discard_blocks(xi->logdev, xi->logBBsize, quiet);
 }
 
 static void
@@ -3749,7 +3773,7 @@ main(
 	 * All values have been validated, discard the old device layout.
 	 */
 	if (discard && !dry_run)
-		discard_devices(&xi);
+		discard_devices(&xi, quiet);
 
 	/*
 	 * we need the libxfs buffer cache from here on in.
-- 
2.23.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

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Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-28  6:21 [PATCH v3] mkfs: Break block discard into chunks of 2 GB Pavel Reichl
2019-11-30 22:01 ` Chaitanya Kulkarni
2019-12-02 16:40   ` Darrick J. Wong
2019-12-04 16:24   ` Eric Sandeen
2019-12-04 17:26     ` Christoph Hellwig
2019-12-04 17:32       ` Eric Sandeen
2019-12-04 17:42       ` Darrick J. Wong
2019-12-10  7:33         ` Chaitanya Kulkarni
2019-12-10 14:20           ` Eric Sandeen
2019-12-09 22:00 ` Eric Sandeen
2019-12-09 23:34   ` Darrick J. Wong
2019-12-10  0:49     ` Eric Sandeen

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