[xfsprogs] xfs_io: add FALLOC_FL_WRITE_ZEROES support

Commit Message

Zhang Yi March 18, 2025, 7:23 a.m. UTC

From: Zhang Yi <[e-mail]>

The Linux kernel is planning to support FALLOC_FL_WRITE_ZEROES in
fallocate(2). Add FALLOC_FL_ZERO_RANGE support to fallocate utility by
introducing a new 'fwzero' command to xfs_io.

Signed-off-by: Zhang Yi <[e-mail]>
---
 io/prealloc.c     | 36 ++++++++++++++++++++++++++++++++++++
 man/man8/xfs_io.8 |  5 +++++
 2 files changed, 41 insertions(+)

Patch

diff --git a/io/prealloc.c b/io/prealloc.c
index 8e968c9f..9d126229 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 writing zeroes");
+	add_command(&fwzero_cmd);
 }
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 59d5ddc5..718f018c 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -538,6 +538,11 @@  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 writing zeroes.
+.TP
 .BI zero " offset length"
 Call xfsctl with
 .B XFS_IOC_ZERO_RANGE