[v2] xfs_io: add FALLOC_FL_WRITE_ZEROES support

[PATCH xfsprogs v2] xfs_io: add FALLOC_FL_WRITE_ZEROES support

Posted by Zhang Yi 1 month, 3 weeks ago

From: Zhang Yi <yi.zhang@huawei.com>

The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in
fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the
fallocate utility by introducing a new 'fwzero' command in the xfs_io
tool.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
v1->v2:
 - Minor description modification to align with the kernel.

 io/prealloc.c     | 36 ++++++++++++++++++++++++++++++++++++
 man/man8/xfs_io.8 |  6 ++++++
 2 files changed, 42 insertions(+)

diff --git a/io/prealloc.c b/io/prealloc.c
index 8e968c9f..9a64bf53 100644
--- a/io/prealloc.c
+++ b/io/prealloc.c
@@ -30,6 +30,10 @@
 #define FALLOC_FL_UNSHARE_RANGE 0x40
 #endif
 
+#ifndef FALLOC_FL_WRITE_ZEROES
+#define FALLOC_FL_WRITE_ZEROES 0x80
+#endif
+
 static cmdinfo_t allocsp_cmd;
 static cmdinfo_t freesp_cmd;
 static cmdinfo_t resvsp_cmd;
@@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd;
 static cmdinfo_t finsert_cmd;
 static cmdinfo_t fzero_cmd;
 static cmdinfo_t funshare_cmd;
+static cmdinfo_t fwzero_cmd;
 
 static int
 offset_length(
@@ -377,6 +382,27 @@ funshare_f(
 	return 0;
 }
 
+static int
+fwzero_f(
+	int		argc,
+	char		**argv)
+{
+	xfs_flock64_t	segment;
+	int		mode = FALLOC_FL_WRITE_ZEROES;
+
+	if (!offset_length(argv[1], argv[2], &segment)) {
+		exitcode = 1;
+		return 0;
+	}
+
+	if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) {
+		perror("fallocate");
+		exitcode = 1;
+		return 0;
+	}
+	return 0;
+}
+
 void
 prealloc_init(void)
 {
@@ -489,4 +515,14 @@ prealloc_init(void)
 	funshare_cmd.oneline =
 	_("unshares shared blocks within the range");
 	add_command(&funshare_cmd);
+
+	fwzero_cmd.name = "fwzero";
+	fwzero_cmd.cfunc = fwzero_f;
+	fwzero_cmd.argmin = 2;
+	fwzero_cmd.argmax = 2;
+	fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+	fwzero_cmd.args = _("off len");
+	fwzero_cmd.oneline =
+	_("zeroes space and eliminates holes by allocating and submitting write zeroes");
+	add_command(&fwzero_cmd);
 }
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index b0dcfdb7..0a673322 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -550,6 +550,12 @@ With the
 .B -k
 option, use the FALLOC_FL_KEEP_SIZE flag as well.
 .TP
+.BI fwzero " offset length"
+Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the
+.BR fallocate (2)
+manual page to allocate and zero blocks within the range by submitting write
+zeroes.
+.TP
 .BI zero " offset length"
 Call xfsctl with
 .B XFS_IOC_ZERO_RANGE
-- 
2.39.2

Re: [PATCH xfsprogs v2] xfs_io: add FALLOC_FL_WRITE_ZEROES support

Posted by Darrick J. Wong 1 month, 3 weeks ago

On Wed, Aug 13, 2025 at 10:42:50AM +0800, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in
> fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the
> fallocate utility by introducing a new 'fwzero' command in the xfs_io
> tool.
> 
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
> v1->v2:
>  - Minor description modification to align with the kernel.
> 
>  io/prealloc.c     | 36 ++++++++++++++++++++++++++++++++++++
>  man/man8/xfs_io.8 |  6 ++++++
>  2 files changed, 42 insertions(+)
> 
> diff --git a/io/prealloc.c b/io/prealloc.c
> index 8e968c9f..9a64bf53 100644
> --- a/io/prealloc.c
> +++ b/io/prealloc.c
> @@ -30,6 +30,10 @@
>  #define FALLOC_FL_UNSHARE_RANGE 0x40
>  #endif
>  
> +#ifndef FALLOC_FL_WRITE_ZEROES
> +#define FALLOC_FL_WRITE_ZEROES 0x80
> +#endif
> +
>  static cmdinfo_t allocsp_cmd;
>  static cmdinfo_t freesp_cmd;
>  static cmdinfo_t resvsp_cmd;
> @@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd;
>  static cmdinfo_t finsert_cmd;
>  static cmdinfo_t fzero_cmd;
>  static cmdinfo_t funshare_cmd;
> +static cmdinfo_t fwzero_cmd;
>  
>  static int
>  offset_length(
> @@ -377,6 +382,27 @@ funshare_f(
>  	return 0;
>  }
>  
> +static int
> +fwzero_f(
> +	int		argc,
> +	char		**argv)
> +{
> +	xfs_flock64_t	segment;
> +	int		mode = FALLOC_FL_WRITE_ZEROES;

Shouldn't this take a -k to add FALLOC_FL_KEEP_SIZE like fzero?

(The code otherwise looks fine to me)

--D

> +
> +	if (!offset_length(argv[1], argv[2], &segment)) {
> +		exitcode = 1;
> +		return 0;
> +	}
> +
> +	if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) {
> +		perror("fallocate");
> +		exitcode = 1;
> +		return 0;
> +	}
> +	return 0;
> +}
> +
>  void
>  prealloc_init(void)
>  {
> @@ -489,4 +515,14 @@ prealloc_init(void)
>  	funshare_cmd.oneline =
>  	_("unshares shared blocks within the range");
>  	add_command(&funshare_cmd);
> +
> +	fwzero_cmd.name = "fwzero";
> +	fwzero_cmd.cfunc = fwzero_f;
> +	fwzero_cmd.argmin = 2;
> +	fwzero_cmd.argmax = 2;
> +	fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
> +	fwzero_cmd.args = _("off len");
> +	fwzero_cmd.oneline =
> +	_("zeroes space and eliminates holes by allocating and submitting write zeroes");
> +	add_command(&fwzero_cmd);
>  }
> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> index b0dcfdb7..0a673322 100644
> --- a/man/man8/xfs_io.8
> +++ b/man/man8/xfs_io.8
> @@ -550,6 +550,12 @@ With the
>  .B -k
>  option, use the FALLOC_FL_KEEP_SIZE flag as well.
>  .TP
> +.BI fwzero " offset length"
> +Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the
> +.BR fallocate (2)
> +manual page to allocate and zero blocks within the range by submitting write
> +zeroes.
> +.TP
>  .BI zero " offset length"
>  Call xfsctl with
>  .B XFS_IOC_ZERO_RANGE
> -- 
> 2.39.2
> 
>

Re: [PATCH xfsprogs v2] xfs_io: add FALLOC_FL_WRITE_ZEROES support

Posted by Zhang Yi 1 month, 2 weeks ago

On 2025/8/15 0:54, Darrick J. Wong wrote:
> On Wed, Aug 13, 2025 at 10:42:50AM +0800, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in
>> fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the
>> fallocate utility by introducing a new 'fwzero' command in the xfs_io
>> tool.
>>
>> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c
>> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
>> ---
>> v1->v2:
>>  - Minor description modification to align with the kernel.
>>
>>  io/prealloc.c     | 36 ++++++++++++++++++++++++++++++++++++
>>  man/man8/xfs_io.8 |  6 ++++++
>>  2 files changed, 42 insertions(+)
>>
>> diff --git a/io/prealloc.c b/io/prealloc.c
>> index 8e968c9f..9a64bf53 100644
>> --- a/io/prealloc.c
>> +++ b/io/prealloc.c
>> @@ -30,6 +30,10 @@
>>  #define FALLOC_FL_UNSHARE_RANGE 0x40
>>  #endif
>>  
>> +#ifndef FALLOC_FL_WRITE_ZEROES
>> +#define FALLOC_FL_WRITE_ZEROES 0x80
>> +#endif
>> +
>>  static cmdinfo_t allocsp_cmd;
>>  static cmdinfo_t freesp_cmd;
>>  static cmdinfo_t resvsp_cmd;
>> @@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd;
>>  static cmdinfo_t finsert_cmd;
>>  static cmdinfo_t fzero_cmd;
>>  static cmdinfo_t funshare_cmd;
>> +static cmdinfo_t fwzero_cmd;
>>  
>>  static int
>>  offset_length(
>> @@ -377,6 +382,27 @@ funshare_f(
>>  	return 0;
>>  }
>>  
>> +static int
>> +fwzero_f(
>> +	int		argc,
>> +	char		**argv)
>> +{
>> +	xfs_flock64_t	segment;
>> +	int		mode = FALLOC_FL_WRITE_ZEROES;
> 
> Shouldn't this take a -k to add FALLOC_FL_KEEP_SIZE like fzero?
> 

Since allocating blocks with written extents beyond the inode size
is not permitted, the FALLOC_FL_WRITE_ZEROES flag cannot be used
together with the FALLOC_FL_KEEP_SIZE.

Thanks,
Yi.

> (The code otherwise looks fine to me)
> 
> --D
> 
>> +
>> +	if (!offset_length(argv[1], argv[2], &segment)) {
>> +		exitcode = 1;
>> +		return 0;
>> +	}
>> +
>> +	if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) {
>> +		perror("fallocate");
>> +		exitcode = 1;
>> +		return 0;
>> +	}
>> +	return 0;
>> +}
>> +
>>  void
>>  prealloc_init(void)
>>  {
>> @@ -489,4 +515,14 @@ prealloc_init(void)
>>  	funshare_cmd.oneline =
>>  	_("unshares shared blocks within the range");
>>  	add_command(&funshare_cmd);
>> +
>> +	fwzero_cmd.name = "fwzero";
>> +	fwzero_cmd.cfunc = fwzero_f;
>> +	fwzero_cmd.argmin = 2;
>> +	fwzero_cmd.argmax = 2;
>> +	fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
>> +	fwzero_cmd.args = _("off len");
>> +	fwzero_cmd.oneline =
>> +	_("zeroes space and eliminates holes by allocating and submitting write zeroes");
>> +	add_command(&fwzero_cmd);
>>  }
>> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
>> index b0dcfdb7..0a673322 100644
>> --- a/man/man8/xfs_io.8
>> +++ b/man/man8/xfs_io.8
>> @@ -550,6 +550,12 @@ With the
>>  .B -k
>>  option, use the FALLOC_FL_KEEP_SIZE flag as well.
>>  .TP
>> +.BI fwzero " offset length"
>> +Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the
>> +.BR fallocate (2)
>> +manual page to allocate and zero blocks within the range by submitting write
>> +zeroes.
>> +.TP
>>  .BI zero " offset length"
>>  Call xfsctl with
>>  .B XFS_IOC_ZERO_RANGE
>> -- 
>> 2.39.2
>>
>>

Re: [PATCH xfsprogs v2] xfs_io: add FALLOC_FL_WRITE_ZEROES support

Posted by Darrick J. Wong 1 month, 2 weeks ago

On Fri, Aug 15, 2025 at 05:59:01PM +0800, Zhang Yi wrote:
> On 2025/8/15 0:54, Darrick J. Wong wrote:
> > On Wed, Aug 13, 2025 at 10:42:50AM +0800, Zhang Yi wrote:
> >> From: Zhang Yi <yi.zhang@huawei.com>
> >>
> >> The Linux kernel (since version 6.17) supports FALLOC_FL_WRITE_ZEROES in
> >> fallocate(2). Add support for FALLOC_FL_WRITE_ZEROES support to the
> >> fallocate utility by introducing a new 'fwzero' command in the xfs_io
> >> tool.
> >>
> >> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=278c7d9b5e0c
> >> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> >> ---
> >> v1->v2:
> >>  - Minor description modification to align with the kernel.
> >>
> >>  io/prealloc.c     | 36 ++++++++++++++++++++++++++++++++++++
> >>  man/man8/xfs_io.8 |  6 ++++++
> >>  2 files changed, 42 insertions(+)
> >>
> >> diff --git a/io/prealloc.c b/io/prealloc.c
> >> index 8e968c9f..9a64bf53 100644
> >> --- a/io/prealloc.c
> >> +++ b/io/prealloc.c
> >> @@ -30,6 +30,10 @@
> >>  #define FALLOC_FL_UNSHARE_RANGE 0x40
> >>  #endif
> >>  
> >> +#ifndef FALLOC_FL_WRITE_ZEROES
> >> +#define FALLOC_FL_WRITE_ZEROES 0x80
> >> +#endif
> >> +
> >>  static cmdinfo_t allocsp_cmd;
> >>  static cmdinfo_t freesp_cmd;
> >>  static cmdinfo_t resvsp_cmd;
> >> @@ -41,6 +45,7 @@ static cmdinfo_t fcollapse_cmd;
> >>  static cmdinfo_t finsert_cmd;
> >>  static cmdinfo_t fzero_cmd;
> >>  static cmdinfo_t funshare_cmd;
> >> +static cmdinfo_t fwzero_cmd;
> >>  
> >>  static int
> >>  offset_length(
> >> @@ -377,6 +382,27 @@ funshare_f(
> >>  	return 0;
> >>  }
> >>  
> >> +static int
> >> +fwzero_f(
> >> +	int		argc,
> >> +	char		**argv)
> >> +{
> >> +	xfs_flock64_t	segment;
> >> +	int		mode = FALLOC_FL_WRITE_ZEROES;
> > 
> > Shouldn't this take a -k to add FALLOC_FL_KEEP_SIZE like fzero?
> > 
> 
> Since allocating blocks with written extents beyond the inode size
> is not permitted, the FALLOC_FL_WRITE_ZEROES flag cannot be used
> together with the FALLOC_FL_KEEP_SIZE.

Heh, apparently I didn't read the manpage well enough.

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D


> Thanks,
> Yi.
> 
> > (The code otherwise looks fine to me)
> > 
> > --D
> > 
> >> +
> >> +	if (!offset_length(argv[1], argv[2], &segment)) {
> >> +		exitcode = 1;
> >> +		return 0;
> >> +	}
> >> +
> >> +	if (fallocate(file->fd, mode, segment.l_start, segment.l_len)) {
> >> +		perror("fallocate");
> >> +		exitcode = 1;
> >> +		return 0;
> >> +	}
> >> +	return 0;
> >> +}
> >> +
> >>  void
> >>  prealloc_init(void)
> >>  {
> >> @@ -489,4 +515,14 @@ prealloc_init(void)
> >>  	funshare_cmd.oneline =
> >>  	_("unshares shared blocks within the range");
> >>  	add_command(&funshare_cmd);
> >> +
> >> +	fwzero_cmd.name = "fwzero";
> >> +	fwzero_cmd.cfunc = fwzero_f;
> >> +	fwzero_cmd.argmin = 2;
> >> +	fwzero_cmd.argmax = 2;
> >> +	fwzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
> >> +	fwzero_cmd.args = _("off len");
> >> +	fwzero_cmd.oneline =
> >> +	_("zeroes space and eliminates holes by allocating and submitting write zeroes");
> >> +	add_command(&fwzero_cmd);
> >>  }
> >> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> >> index b0dcfdb7..0a673322 100644
> >> --- a/man/man8/xfs_io.8
> >> +++ b/man/man8/xfs_io.8
> >> @@ -550,6 +550,12 @@ With the
> >>  .B -k
> >>  option, use the FALLOC_FL_KEEP_SIZE flag as well.
> >>  .TP
> >> +.BI fwzero " offset length"
> >> +Call fallocate with FALLOC_FL_WRITE_ZEROES flag as described in the
> >> +.BR fallocate (2)
> >> +manual page to allocate and zero blocks within the range by submitting write
> >> +zeroes.
> >> +.TP
> >>  .BI zero " offset length"
> >>  Call xfsctl with
> >>  .B XFS_IOC_ZERO_RANGE
> >> -- 
> >> 2.39.2
> >>
> >>
> 
>