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[PATCH] xfs_io: add mremap command

To: xfs-oss <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs_io: add mremap command
From: Eric Sandeen <sandeen@xxxxxxxxxx>
Date: Wed, 10 Sep 2014 22:25:04 -0500
Delivered-to: xfs@xxxxxxxxxxx
This adds a simple mremap command to xfs_io.

It does not take a start address; it uses the existing
start address, so the sized passed will be the new total
size of the mapping.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---

diff --git a/io/mmap.c b/io/mmap.c
index ea7498f..565a541 100644
--- a/io/mmap.c
+++ b/io/mmap.c
@@ -29,6 +29,7 @@ static cmdinfo_t mread_cmd;
 static cmdinfo_t msync_cmd;
 static cmdinfo_t munmap_cmd;
 static cmdinfo_t mwrite_cmd;
+static cmdinfo_t mremap_cmd;
mmap_region_t *maptable;
 int            mapcount;
@@ -574,6 +575,66 @@ mwrite_f(
        return 0;
 }
+static void
+mremap_help(void)
+{
+       printf(_(
+"\n"
+" resizes the current memory mapping\n"
+"\n"
+" Examples:\n"
+" 'mremap 8192' - resizes the current mapping to 8192 bytes.\n"
+"\n"
+" Resizes the mappping, growing or shrinking from the current size.\n"
+" The default stored value is 'X', repeated to fill the range specified.\n"
+" -f -- use the MREMAP_FIXED flag\n"
+" -m -- use the MREMAP_MAYMOVE flag\n"
+"\n"));
+}
+
+int
+mremap_f(
+       int             argc,
+       char            **argv)
+{
+       ssize_t         new_length;
+       void            *new_addr;
+       int             flags = 0;
+       int             c;
+       size_t          blocksize, sectsize;
+
+       while ((c = getopt(argc, argv, "fm")) != EOF) {
+               switch (c) {
+               case 'f':
+                       flags = MREMAP_FIXED|MREMAP_MAYMOVE;
+                       break;
+               case 'm':
+                       flags = MREMAP_MAYMOVE;
+                       break;
+               default:
+                       return command_usage(&mremap_cmd);
+               }
+       }
+
+       init_cvtnum(&blocksize, &sectsize);
+       new_length = cvtnum(blocksize, sectsize, argv[optind]);
+       if (new_length < 0) {
+               printf(_("non-numeric offset argument -- %s\n"),
+                       argv[optind]);
+               return 0;
+       }
+
+       new_addr = mremap(mapping->addr, mapping->length, new_length, flags);
+       if (new_addr == MAP_FAILED)
+               perror("mremap");
+       else {
+               mapping->addr = new_addr;
+               mapping->length = new_length;
+       }
+
+       return 0;
+}
+
 void
 mmap_init(void)
 {
@@ -628,9 +689,21 @@ mmap_init(void)
                _("writes data into a region in the current memory mapping");
        mwrite_cmd.help = mwrite_help;
+ mremap_cmd.name = "mremap";
+       mremap_cmd.altname = "mrm";
+       mremap_cmd.cfunc = mremap_f;
+       mremap_cmd.argmin = 1;
+       mremap_cmd.argmax = 2;
+       mremap_cmd.flags = CMD_NOFILE_OK | CMD_FOREIGN_OK;
+       mremap_cmd.args = _("[-f|-m] newsize");
+       mremap_cmd.oneline =
+               _("alters the size of the current memory mapping");
+       mremap_cmd.help = mremap_help;
+
        add_command(&mmap_cmd);
        add_command(&mread_cmd);
        add_command(&msync_cmd);
        add_command(&munmap_cmd);
        add_command(&mwrite_cmd);
+       add_command(&mremap_cmd);
 }
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index e1a3e1a..e40fbf9 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -501,6 +501,20 @@ See the
 .B mmap
 command.
 .TP
+.BI "mremap [ \-f ] [ \-m ] " new_length
+Changes the current mapping size to
+.IR new_length .
+Whether the mapping may be moved is controlled by the flags passed;
+MREMAP_FIXED
+.RB ( \-f ),
+or MREMAP_MAYMOVE
+.RB ( \-m ).
+.TP
+.B mrm
+See the
+.B mremap
+command.
+.TP
 .B munmap
 Unmaps the current memory mapping.
 .TP

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