btrfs-progs: Add minimum device size check CHECKME

Btrfs has global block reservation, so even mkfs.btrfs can execute
without problem, there is still a possibility that the filesystem can't
be mounted.
For example when mkfs.btrfs on a 8M file on x86_64 platform, kernel will
refuse to mount due to ENOSPC, since system block group takes 4M and
mixed block group takes 4M, and global block reservation will takes all
the 4M from mixed block group, which makes btrfs unable to create uuid
tree.

This patch will add minimum device size check before actually mkfs.
The minimum size calculation uses a simplified one:
minimum_size_for_each_dev = 2 * (system block group + global block rsv)
and global block rsv = leafsize << 10

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[minor wording tweaks in messages]
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: add supported attr flags to btrfs(5)

The chattr(1) manpage suffers from the same problems mount(1)
had: many options listed, not kept up to date for various
filesystems.

I've submitted a manpage update for chattr(1) which says to
refer to filesystem-specific manpages for supported attributes;
this patch updates btrfs(5) to list the attributes supported
by btrfs.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
[added some asciidoc markups, adjusted formatting]
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: replace BTRFS_NUM_MIRRORS with BTRFS_MAX_MIRRORS

The chunk-recover.c/BTRFS_NUM_MIRRORS in the userspace means
the same thing as ctree.h/BTRFS_MAX_MIRRORS in the kernelspace,
so to stay consistent with the kernelspace, just make this movement
in the userspace:
	chunk-recover.c/BTRFS_NUM_MIRRORS
		===>
	ctree.h/BTRFS_MAX_MIRRORS

This provides convenience for future use.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: deal with malloc failure in btrfs-image

Handle the malloc failure for dump_worker in the same way as
the restore worker.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: cleanup possible silent failure in btrfs-image

If the malloc above fails, the btrfs-image will exit directly
without any error messages.
Now just return the ENOMEM errno and let the caller prompt the
error message.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: use BTRFS_SUPER_INFO_SIZE to replace raw 4096 in btrfs-image

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: Avoid double-free of fs_devices->list

I found the following patch is insufficient.

===============================================================================
commit 6e6b32ddf58db54f714d0f263c2589f4859e8b5e
Author: Adam Buchbinder <abuchbinder@google.com>
Date:   Fri Jun 13 16:43:56 2014 -0700

    btrfs-progs: Fix a use-after-free in the volumes code.
===============================================================================

"btrfs filesystem show <dev>" with this patch causes segmentation fault
if "<dev>" is a not-mounted Btrfs filesystem.

===============================================================================
Label: none  uuid: <cut here>
        Total devices 1 FS bytes used 112.00KiB
        devid    1 size 59.12GiB used 2.04GiB path /dev/sdd1

Segmentation fault (core dumped)
===============================================================================

It's due to double-free of fs_devices->list as follows.

===============================================================================
cmd_show
  -> list_del(&fs_devices->list)     # 1st one.
  -> btrfs_close_devices(fs_devices)
    -> list_del(&fs_devices->list)   # <- 2nd one introduced at 6e6b32dd.
                                          Double-free happens here.
===============================================================================

First list_del() can safely be removed because fs_devices->list will be
deleted by second one, soon.

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Adam Buchbinder <abuchbinder@google.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: fix btrfs-image old_restore fsck failure

Steps to reproduce:
	# mkfs.btrfs -f <dev1>
	# btrfs-image <dev1> <image_file>
	# btrfs-image -r -o <image_file> <dev2>
	# btrfs check <dev2>

btrfs check output:
	: read block failed check_tree_block
	: Couldn't read tree root
	: Couldn't open file system

The btrfs-image should not mess with the chunk tree under the old_restore way.

The new restore way was introduced by:
	commit d6f7e3da0dae7b60cb7565f8a47c3b9045c52d1d
	Btrfs-progs: make btrfs-image restore with a valid chunk tree V2
	...
And the following commit enhanced the new restore on the valid chunk tree
building stuff:
	commit ef2a8889ef813ba77061f6a92f4954d047a78932
	Btrfs-progs: make image restore with the original device offsets
	...

But the second commit should not effect the old_restore way since the
old_restore way doesn't try to build a valid chunk tree at all.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Btrfs-progs: fsck: reduce memory usage for extents check

Steps to reproduce:

 # mkfs.btrfs -f /dev/sda9 -b 2g
 # mount /dev/sda9 /mnt
 # dd if=/dev/zero of=/mnt/data bs=4k oflag=direct
 # btrfs file df /mnt

    Data, single: total=1.66GiB, used=1.66GiB
    System, single: total=4.00MiB, used=16.00KiB
    Metadata, single: total=200.00MiB, used=67.88MiB

For a filesystem without snapshots, 70M metadata, extent
checking eats max memory about 110M, this is a nightmare
for some system with low memory.

It is very likely that extent record can be freed quickly
for a filesystem without snapshots, improve this by trying
if it can free memory after adding data/tree backrefs.

This patch reduces max memory cost from 110M to 40M for
extents checking for the above case.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: cleanup unnecessary free if malloc fails in btrfs-image

Don't bother free the buffer if the malloc failed.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: add X inode flag to btrfs(5)

After the discussion in
http://thread.gmane.org/gmane.comp.file-systems.btrfs/36334

the 'X' will be mentioned in the manpage because new e2fsprogs/lsattr
will display it and represents the NOCOMPRESS bit of an inode.

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