Defragging an executable conflicts both way with it being run, resulting in ETXTBSY. This either makes defrag fail or prevents the program from being executed.
Kernels 4.19-rc1 and later allow defragging files you could have possibly opened rw, even if the passed descriptor is ro (commit 616d374efa23). Signed-off-by: Adam Borowski <kilob...@angband.pl> --- v2: more eloquent description; root can't defrag RO on old kernels (unlike dedupe) v3: more eloquentier description; s/defrag_ro/defrag_open_mode/ cmds-filesystem.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/cmds-filesystem.c b/cmds-filesystem.c index 06c8311b..99e2aec0 100644 --- a/cmds-filesystem.c +++ b/cmds-filesystem.c @@ -26,6 +26,7 @@ #include <ftw.h> #include <mntent.h> #include <linux/limits.h> +#include <linux/version.h> #include <getopt.h> #include <btrfsutil.h> @@ -39,12 +40,14 @@ #include "list_sort.h" #include "disk-io.h" #include "help.h" +#include "fsfeatures.h" /* * for btrfs fi show, we maintain a hash of fsids we've already printed. * This way we don't print dups if a given FS is mounted more than once. */ static struct seen_fsid *seen_fsid_hash[SEEN_FSID_HASH_SIZE] = {NULL,}; +static mode_t defrag_open_mode = O_RDONLY; static const char * const filesystem_cmd_group_usage[] = { "btrfs filesystem [<group>] <command> [<args>]", @@ -877,7 +880,7 @@ static int defrag_callback(const char *fpath, const struct stat *sb, if ((typeflag == FTW_F) && S_ISREG(sb->st_mode)) { if (defrag_global_verbose) printf("%s\n", fpath); - fd = open(fpath, O_RDWR); + fd = open(fpath, defrag_open_mode); if (fd < 0) { goto error; } @@ -914,6 +917,9 @@ static int cmd_filesystem_defrag(int argc, char **argv) int compress_type = BTRFS_COMPRESS_NONE; DIR *dirstream; + if (get_running_kernel_version() < KERNEL_VERSION(4,19,0)) + defrag_open_mode = O_RDWR; + /* * 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 @@ -1014,7 +1020,7 @@ static int cmd_filesystem_defrag(int argc, char **argv) int defrag_err = 0; dirstream = NULL; - fd = open_file_or_dir(argv[i], &dirstream); + fd = open_file_or_dir3(argv[i], &dirstream, defrag_open_mode); if (fd < 0) { error("cannot open %s: %m", argv[i]); ret = -errno; -- 2.19.0.rc1