btrfs-progs: remove false dependency on libm

It ends up in the final binary, but there are not math functions used.

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Makefile: Move linker only option to LDFLAGS

Move the linker only option -rdynamic to LDFLAGS.
This resolve lots of the following warning if using clang as CC:
clang: warning: argument unused during compilation: '-rdynamic'

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Fix a clang dead-judgement warning in disk-io.c.

When compiled with clang, the following warning is outputted.

disk-io.c:1017:15: warning: comparison of unsigned expression < 0 is
always false [-Wtautological-compare]
        if (dev_size < 0)
            ~~~~~~~~ ^ ~
1 warning generated.

This is because dev_size is defined as unsigned type, but lseek() will
return singed valued.
So the judgement will always to false.

Use temporary off_t return value to solve it.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Remove a unused function root_gtp_mask().

Fix the following clang warning when compiling btrfs-progs:

radix-tree.c:78:21: warning: unused function 'root_gfp_mask'
[-Wunused-function]
static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
                    ^
1 warning generated.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Remove a unused function offset_to_bitmap()

Fix the following clang warning:

free-space-cache.c:464:19: warning: unused function 'offset_to_bitmap'
[-Wunused-function]
static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
                  ^
1 warning generated.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Remove deprecated _BSD_SOURCE macro.

Fix the following gcc(>4.9) and clang warning:

In file included from cmds-receive.c:24:
In file included from ./kerncompat.h:22:
In file included from /usr/include/stdio.h:27:
/usr/include/features.h:148:3: warning: "_BSD_SOURCE and _SVID_SOURCE
are deprecated, use _DEFAULT_SOURCE" [-W#warnings]
  ^
1 warning generated.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Enhance the document of btrfs property

Enhance the document of btrfs property as follows.

- Add the description about the candidates of <name>.
- Enrich the description of <object>.
- Fix typos and some redundancy.

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Reported-by: Naohiro Aota <naota@elisp.net>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: cleanup: avoid to use literal for getopt val

Signed-off-by: David Sterba <dsterba@suse.cz>