This commit changes the btrfs send/receive commands to use the
UUID tree to map UUIDs to subvolumes, and to use the root tree
to map subvolume IDs to paths. Now these tools start fast and are
independent on the number of subvolules/snapshot that exist.
Before this commit, mapping UUIDs to subvolume IDs was an operation
with a high effort. The algorithm even had quadratic effort (based
on the number of existing subvolumes). E.g. with 15,000 subvolumes
it took much more than 5 minutes on a state of the art XEON CPU to
start btrfs send or receive before these tools were able to send or
receive the first byte).
Even linear effort instead of the current quadratic effort would be
too much since it would be a waste. And these data structures to
allow mapping UUIDs to subvolume IDs had been created every time a
btrfs send/receive instance was started.
It is much more efficient to maintain a searchable persistent data
structure in the filesystem, one that is updated whenever a
subvolume/snapshot is created and deleted, and when the received
subvolume UUID is set by the btrfs-receive tool.
Therefore kernel code was added that is able to maintain data
structures in the filesystem that allow to quickly search for a
given UUID and to retrieve data that is assigned to this UUID, like
which subvolume ID is related to this UUID.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Several tools like btrfs-send and btrfs-receive need to map a
subvolume ID to a filesystem path. The so far existing methods
in btrfs-list.c cause a horrible effort when performing this
operation (and the effort is dependent on the number of
existing subvolumes with quadratic effort). This commit adds a
function that is able to map a subvolume ID to a filesystem path
with an effort that is independent of the number of existing
subvolumes.
In addition to this function, a command line frontend is added as well:
btrfs inspect-internal subvolid-resolve <subvolid> <path>
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
There was no way to free the memory that was used for the
subvol_uuid_search functions. Since this is part of the libbtrfs,
add such a cleanup function.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
We missed to add the default subvolume, because it has no ROOT_BACKREF_ITEM.
This made get_parent always fail for direct decendants of the default
subvolume, resulting in lots of full streams where incremental streams were
requested.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Reviewed-by: Alexander Block <ablock84@googlemail.com>
The current code of list_subvols() has very bad scalability, if we want to
add new filter conditions or new sort methods, we have to modify lots of code.
Beside that, the most code of list_snapshots() is similar to list_subvols(),
So I restructure list_subvols(), and split the subvolume filter function,
the subvolume sort function and the output function from list_subvols().
In order to implement it, we defined some importtant structures:
struct btrfs_list_filter {
btrfs_list_filter_func filter_func;
void *data;
};
struct btrfs_list_comparer {
btrfs_list_comp_func comp_func;
int is_descending;
};
struct {
char *name;
char *column_name;
int need_print;
} btrfs_list_columns[];
If we want to add a new filter condition, we can choose a suitable filter
function, or implement a new filter function[1], and add it into a set of
the filters, and then pass the filter set into list_subvols(). We also can
mix several filters (just add those filters into the set, and pass the set
into list_subvols()) if the users specify two or more filter conditions.
The subvolume sort function is similar to the subvolume filter function. The
differentiation is the order of comparers in the array which is passed into
list_subvols() show us the priority of the sort methods.
The output function is different with the above two functions, we define a
array to manage all the columns that can be outputed, and use a member variant
(->need_print) to control the output of the relative column. Some columns are
outputed by default. But we can change it according to the requirement of the
users.
After appling this patch, we needn't implement a independent list_snapshots()
function, just pass a filter function which is used to identify the snapshot
into list_subvols().
[1]: If we implement new filter functions or compare functions, we must add
them into the array all_filter_funcs or the array all_comp_funcs, and modify
the relative enum variants(btrfs_list_filter_enum, btrfs_list_comp_enum).
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
This patch fixed the following warning:
cmds-send.c:464:6: warning: ‘ret' may be used uninitialized in this function [-Wuninitialized]
crc32c.c:121:1: warning: control reaches end of non-void function [-Wreturn-type]
send-utils.c:69:11: warning: ‘comp' may be used uninitialized in this function [-Wuninitialized]
send-utils.c:126:6: warning: ‘comp' may be used uninitialized in this function [-Wuninitialized]
send-utils.c:99:22: warning: ‘entry' may be used uninitialized in this function [-Wuninitialized]
btrfs.c:261:2: warning: implicit declaration of function ‘crc32c_optimization_init' [-Wimplicit-function-declaration]
btrfs.c:105:2: warning: ‘cmd' may be used uninitialized in this function [-Wuninitialized]
restore.c:435:12: warning: ignoring return value of ‘ftruncate', declared with attribute warn_unused_result [-Wunused-result]
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
The initial btrfs send code was easily confused by relative paths and by
anything that wasn't in the root of the FS. This fixes it to take
relative paths.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Add user space commands for btrfs send/receive.
Signed-off-by: Alexander Block <ablock84@googlemail.com>
Reviewed-by: David Sterba <dave@jikos.cz>
Reviewed-by: Arne Jansen <sensille@gmx.net>
Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Reviewed-by: Alex Lyakas <alex.bolshoy.btrfs@gmail.com>
Stefan Behrens
Jan Schmidt
Miao Xie
Zhou Bo
Chris Mason
Alexander Block