[PATCH] fix extent length in xfs_io bmap

[Utako Kusaka <utako@xxxxxxxxxxxxxx>]

Hi,

In bmap command in xfs_io, there is a difference in the length of the extent 
group
between "bmap" and "bmap -n nn". 
It occurs if the file size > max extent size and the extents are allocated 
contiguously.
This patch fixes it.

Test fs:
# xfs_info /dev/sx8/14p1
meta-data=/dev/sx8/14p1          isize=256    agcount=16, agsize=7631000 blks
         =                       sectsz=512   attr=0
data     =                       bsize=4096   blocks=122096000, imaxpct=25
         =                       sunit=0      swidth=0 blks, unwritten=1
naming   =version 2              bsize=4096
log      =internal               bsize=4096   blocks=32768, version=1
         =                       sectsz=512   sunit=0 blks
realtime =none                   extsz=4096   blocks=0, rtextents=0


Example:
u.bmx[0-5] = [startoff,startblock,blockcount,extentflag]
 0:[      0, 1048588,2097088,0]
 1:[2097088, 3145676,2097088,0]
 2:[4194176, 5242764,2097088,0]
 3:[6291264, 7339852, 291136,0]
 4:[6582400, 8388616,2097088,0]
 5:[8679488,10485704,1806272,0]

# xfs_io file2
xfs_io> bmap -v
file2:
 EXT: FILE-OFFSET           BLOCK-RANGE        AG AG-OFFSET              TOTAL
   0: [0..52659199]:        8388704..61047903   0 (8388704..61047903) 52659200  
 ...*
   1: [52659200..83886079]: 61048064..92274943  1 (64..31226943)      31226880  
 ...**
xfs_io> bmap -v -n 1
file2:
 EXT: FILE-OFFSET      BLOCK-RANGE       AG AG-OFFSET              TOTAL
   0: [0..16776703]:   8388704..25165407  0 (8388704..25165407) 16776704        
 ...*
xfs_io> bmap -v -n 2
file2:
 EXT: FILE-OFFSET           BLOCK-RANGE        AG AG-OFFSET              TOTAL
   0: [0..52659199]:        8388704..61047903   0 (8388704..61047903) 52659200
   1: [52659200..69435903]: 61048064..77824767  1 (64..16776767)      16776704  
 ...**


Signed-off-by: Utako Kusaka <utako@xxxxxxxxxxxxxx>
---

--- xfsprogs-2.8.18-orgn/io/bmap.c      2006-12-13 13:57:22.000000000 +0900
+++ xfsprogs-2.8.18/io/bmap.c   2006-12-21 11:07:09.573116475 +0900
@@ -78,6 +78,7 @@ bmap_f(
        int                     bmv_iflags = 0; /* flags for XFS_IOC_GETBMAPX */
        int                     i = 0;
        int                     c;
+       int                     egcnt;
 
        while ((c = getopt(argc, argv, "adln:pv")) != EOF) {
                switch (c) {
@@ -136,7 +137,7 @@ bmap_f(
                }
        }
 
-       map_size = nflag ? nflag+1 : 32;        /* initial guess - 256 */
+       map_size = nflag ? nflag+2 : 32;        /* initial guess - 256 */
        map = malloc(map_size*sizeof(*map));
        if (map == NULL) {
                fprintf(stderr, _("%s: malloc of %d bytes failed.\n"),
@@ -232,9 +233,10 @@ bmap_f(
                        return 0;
                }
        }
+       egcnt = nflag ? min(nflag, map->bmv_entries) : map->bmv_entries;
        printf("%s:\n", file->name);
        if (!vflag) {
-               for (i = 0; i < map->bmv_entries; i++) {
+               for (i = 0; i < egcnt; i++) {
                        printf("\t%d: [%lld..%lld]: ", i,
                                (long long) map[i + 1].bmv_offset,
                                (long long)(map[i + 1].bmv_offset +
@@ -288,7 +290,7 @@ bmap_f(
                 * Go through the extents and figure out the width
                 * needed for all columns.
                 */
-               for (i = 0; i < map->bmv_entries; i++) {
+               for (i = 0; i < egcnt; i++) {
                        snprintf(rbuf, sizeof(rbuf), "[%lld..%lld]:",
                                (long long) map[i + 1].bmv_offset,
                                (long long)(map[i + 1].bmv_offset +
@@ -325,7 +327,7 @@ bmap_f(
                        aoff_w, _("AG-OFFSET"),
                        tot_w, _("TOTAL"),
                        flg ? _(" FLAGS") : "");
-               for (i = 0; i < map->bmv_entries; i++) {
+               for (i = 0; i < egcnt; i++) {
                        flg = FLG_NULL;
                        if (map[i + 1].bmv_oflags & BMV_OF_PREALLOC) {
                                flg |= FLG_PRE;