[PATCH v4] mkfs: Break block discard into chunks of 2 GB

[PATCH v4] mkfs: Break block discard into chunks of 2 GB

[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>
---
Changelog:
	V4: Limit the reporting about discarding to a single line

 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..4bfdebf6 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...");
+		fflush(stdout);
+	}
+
+	/* 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

Re: [PATCH v4] mkfs: Break block discard into chunks of 2 GB

[Pavel Reichl]

Hello,

what do you think about the way 'quiet' var is passed? It doesn't look
as natural parameter to 'discard_devices()' and ' discard_blocks' to
me. What do you think about making 'quiet' a global variable?
Thanks for opinions.

Bye.


On Tue, Dec 10, 2019 at 12:48 PM Pavel Reichl <preichl@redhat.com> wrote:
>
> 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>
> ---
> Changelog:
>         V4: Limit the reporting about discarding to a single line
>
>  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..4bfdebf6 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...");
> +               fflush(stdout);
> +       }
> +
> +       /* 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
>

Re: [PATCH v4] mkfs: Break block discard into chunks of 2 GB

[Eric Sandeen]

On 12/10/19 5:54 AM, Pavel Reichl wrote:
> Hello,
> 
> what do you think about the way 'quiet' var is passed? It doesn't look
> as natural parameter to 'discard_devices()' and ' discard_blocks' to
> me. What do you think about making 'quiet' a global variable?
> Thanks for opinions.
> 
> Bye.

That crossed my mind too, but it doesn't bother me much, I think
it's ok - especially if we can avoid yet another patch version.  ;)

-Eric

Re: [PATCH v4] mkfs: Break block discard into chunks of 2 GB

[Darrick J. Wong]

On Tue, Dec 10, 2019 at 12:48:07PM +0100, Pavel Reichl wrote:
> 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>
> ---
> Changelog:
> 	V4: Limit the reporting about discarding to a single line
> 
>  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..4bfdebf6 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)

If you /do/ decide to make @quiet a global then please make it bool.
That's material for a separate patch though...

...this looks reasonable enough to me;
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D


>  {
> -	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...");
> +		fflush(stdout);
> +	}
> +
> +	/* 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
> 

Re: [PATCH v4] mkfs: Break block discard into chunks of 2 GB

[Dave Chinner]

On Tue, Dec 10, 2019 at 12:48:07PM +0100, Pavel Reichl wrote:
> 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>

Looks fine to me.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com