btrfs-progs: fi defrag: change default extent target size to 32 MiB

[platform/upstream/btrfs-progs.git] / cmds-filesystem.c

diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index ef1f550..00e4bfe 100644 (file)
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -968,7 +968,7 @@ static const char * const cmd_filesystem_defrag_usage[] = {
        "-f             flush data to disk immediately after defragmenting",
        "-s start       defragment only from byte onward",
        "-l len         defragment only up to len bytes",
-       "-t size        target extent size hint",
+       "-t size        target extent size hint (default: 32M)",
        NULL
 };
 
@@ -1029,7 +1029,7 @@ static int cmd_filesystem_defrag(int argc, char **argv)
        int flush = 0;
        u64 start = 0;
        u64 len = (u64)-1;
-       u64 thresh = 0;
+       u64 thresh;
        int i;
        int recursive = 0;
        int ret = 0;
@@ -1037,6 +1037,13 @@ static int cmd_filesystem_defrag(int argc, char **argv)
        int compress_type = BTRFS_COMPRESS_NONE;
        DIR *dirstream;
 
+       /*
+        * Kernel has a different default (256K) that is supposed to be safe,
+        * but it does not defragment very well. The 32M will likely lead to
+        * better results and is independent of the kernel default.
+        */
+       thresh = 32 * 1024 * 1024;
+
        defrag_global_errors = 0;
        defrag_global_verbose = 0;
        defrag_global_errors = 0;