[21/39] xfs_io: try to unshare copy-on-write blocks via fallocate

Commit Message

Darrick J. Wong Oct. 25, 2016, 11:05 p.m. UTC

Wire up the "unshare" flag to the xfs_io fallocate command.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 io/prealloc.c     |   42 ++++++++++++++++++++++++++++++++++++++++--
 man/man8/xfs_io.8 |    5 +++++
 2 files changed, 45 insertions(+), 2 deletions(-)



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Comments

Christoph Hellwig Oct. 26, 2016, 10:34 a.m. UTC | #1

On Tue, Oct 25, 2016 at 04:05:49PM -0700, Darrick J. Wong wrote:
> Wire up the "unshare" flag to the xfs_io fallocate command.

Looks good,

Reviewed-by: Christoph Hellwig <[e-mail]>
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Patch

diff --git a/io/prealloc.c b/io/prealloc.c
index 7f5c200..a9d66cc 100644
--- a/io/prealloc.c
+++ b/io/prealloc.c
@@ -40,6 +40,10 @@ 
 #define FALLOC_FL_INSERT_RANGE 0x20
 #endif
 
+#ifndef FALLOC_FL_UNSHARE_RANGE
+#define FALLOC_FL_UNSHARE_RANGE 0x40
+#endif
+
 static cmdinfo_t allocsp_cmd;
 static cmdinfo_t freesp_cmd;
 static cmdinfo_t resvsp_cmd;
@@ -181,6 +185,7 @@  falloc_help(void)
 " -i -- inserts a hole into the given range of the file.\n"
 " -k -- do not change file size.\n"
 " -p -- unmap the given range from the file.\n"
+" -u -- unshare shared extents in the given range.\n"
 "\n"));
 }
 
@@ -193,7 +198,7 @@  fallocate_f(
 	int		mode = 0;
 	int		c;
 
-	while ((c = getopt(argc, argv, "cikp")) != EOF) {
+	while ((c = getopt(argc, argv, "cikpu")) != EOF) {
 		switch (c) {
 		case 'c':
 			mode = FALLOC_FL_COLLAPSE_RANGE;
@@ -207,6 +212,9 @@  fallocate_f(
 		case 'p':
 			mode = FALLOC_FL_PUNCH_HOLE;
 			break;
+		case 'u':
+			mode = FALLOC_FL_UNSHARE_RANGE;
+			break;
 		default:
 			command_usage(&falloc_cmd);
 		}
@@ -306,6 +314,26 @@  fzero_f(
 	}
 	return 0;
 }
+
+static int
+funshare_f(
+	int		argc,
+	char		**argv)
+{
+	xfs_flock64_t	segment;
+	int		mode = FALLOC_FL_UNSHARE_RANGE;
+	int		index = 1;
+
+	if (!offset_length(argv[index], argv[index + 1], &segment))
+		return 0;
+
+	if (fallocate(file->fd, mode,
+			segment.l_start, segment.l_len)) {
+		perror("fallocate");
+		return 0;
+	}
+	return 0;
+}
 #endif	/* HAVE_FALLOCATE */
 
 void
@@ -366,7 +394,7 @@  prealloc_init(void)
 	falloc_cmd.argmin = 2;
 	falloc_cmd.argmax = -1;
 	falloc_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
-	falloc_cmd.args = _("[-c] [-k] [-p] off len");
+	falloc_cmd.args = _("[-c] [-k] [-p] [-u] off len");
 	falloc_cmd.oneline =
 	_("allocates space associated with part of a file via fallocate");
 	falloc_cmd.help = falloc_help;
@@ -411,5 +439,15 @@  prealloc_init(void)
 	fzero_cmd.oneline =
 	_("zeroes space and eliminates holes by preallocating");
 	add_command(&fzero_cmd);
+
+	fzero_cmd.name = "funshare";
+	fzero_cmd.cfunc = funshare_f;
+	fzero_cmd.argmin = 2;
+	fzero_cmd.argmax = 2;
+	fzero_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+	fzero_cmd.args = _("off len");
+	fzero_cmd.oneline =
+	_("unshares shared blocks within the range");
+	add_command(&fzero_cmd);
 #endif	/* HAVE_FALLOCATE */
 }
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 2365550..eb7b878 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -431,6 +431,11 @@  the FALLOC_FL_PUNCH_HOLE flag as described in the
 .BR fallocate (2)
 manual page.
 .TP
+.BI funshare " offset length"
+Call fallocate with FALLOC_FL_UNSHARE_RANGE flag as described in the
+.BR fallocate (2)
+manual page to unshare all shared blocks within the range.
+.TP
 .BI fzero " offset length"
 Call fallocate with FALLOC_FL_ZERO_RANGE flag as described in the
 .BR fallocate (2)