From e7eaacefff8bc4968143400ba2450abe6ce8d8d5 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Thu, 24 Aug 2017 16:43:44 -0500 Subject: [PATCH] fiemap: Fix semantics of max_extents (-n arguments) Currently the semantics of the -n argument are a bit idiosyncratic. We want the argument to be the limit of extents that are going to be output by the tool. This is clearly broken now as evident from the following example on a fragmented file: xfs_io -c "fiemap -v -n 5" test-dir/fragmented-file test-dir/fragmented-file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..15]: hole 16 1: [16..23]: 897847296..897847303 8 0x0 2: [24..31]: hole 8 3: [32..39]: 897851392..897851399 8 0x0 So we want at most 5 extents printed, yet we get 4. So we always print n - 1 extents. With this modification the output looks like: xfs_io -c "fiemap -v -n 5" test-dir/fragmented-file test-dir/fragmented-file: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..15]: hole 16 1: [16..23]: 897847296..897847303 8 0x0 2: [24..31]: hole 8 3: [32..39]: 897851392..897851399 8 0x0 4: [40..47]: hole 8 Signed-off-by: Nikolay Borisov [sandeen: fix initialization of max_extents] Reviewed-by: Eric Sandeen Reviewed-by: Darrick J. Wong Signed-off-by: Eric Sandeen --- io/fiemap.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/io/fiemap.c b/io/fiemap.c index 44a64870d..e6fd66da7 100644 --- a/io/fiemap.c +++ b/io/fiemap.c @@ -26,7 +26,7 @@ #define EXTENT_BATCH 32 static cmdinfo_t fiemap_cmd; -static int max_extents = 0; +static int max_extents = -1; static void fiemap_help(void) @@ -122,7 +122,7 @@ print_verbose( cur_extent++; } - if ((cur_extent + 1) == max_extents) + if (cur_extent == max_extents) return 1; snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", lstart, @@ -157,7 +157,7 @@ print_plain( cur_extent++; } - if ((cur_extent + 1) == max_extents) + if (cur_extent == max_extents) return 1; printf("\t%d: [%llu..%llu]: %llu..%llu", cur_extent, @@ -264,7 +264,7 @@ fiemap_f( printf("%s:\n", file->name); - while (!last && ((cur_extent + 1) != max_extents)) { + while (!last && (cur_extent != max_extents)) { memset(fiemap, 0, map_size); fiemap->fm_flags = fiemap_flags; @@ -314,12 +314,12 @@ fiemap_f( break; } - if ((cur_extent + 1) == max_extents) + if (cur_extent == max_extents) break; } } - if ((cur_extent + 1) == max_extents) + if (cur_extent == max_extents) goto out; memset(&st, 0, sizeof(st)); -- 2.47.2