From cc25de4aa7e373cb539b6ef7dbea1ea9dc3b4030 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Mon, 11 Jan 2016 12:10:22 -0800 Subject: btrfs-progs: btrfs-debugfs: fetch block group information This aims to decide whether a balance can reduce the number of data block groups and if it is, this shows the '-dvrange' block group's objectid. Signed-off-by: Liu Bo Signed-off-by: David Sterba --- btrfs-debugfs | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 111 insertions(+), 6 deletions(-) (limited to 'btrfs-debugfs') diff --git a/btrfs-debugfs b/btrfs-debugfs index cf1d285c..08e3ec63 100755 --- a/btrfs-debugfs +++ b/btrfs-debugfs @@ -4,7 +4,7 @@ # LGPLv2 license # Copyright Facebook 2014 -import sys,os,struct,fcntl,ctypes,stat +import sys,os,struct,fcntl,ctypes,stat,argparse # helpers for max ints maxu64 = (1L << 64) - 1 @@ -65,6 +65,11 @@ BTRFS_DEV_STATS_KEY = 249 BTRFS_DEV_REPLACE_KEY = 250 BTRFS_STRING_ITEM_KEY = 253 +# store information about which extents are in use, and reference counts +BTRFS_EXTENT_TREE_OBJECTID = 2 + +BTRFS_BLOCK_GROUP_DATA = (1 << 0) + # in the kernel sources, this is flattened # btrfs_ioctl_search_args_v2. It includes both the btrfs_ioctl_search_key # and the buffer. We're using a 64K buffer size. @@ -121,6 +126,13 @@ class btrfs_file_extent_item(ctypes.LittleEndianStructure): ("num_bytes", ctypes.c_ulonglong), ] +class btrfs_block_group_item(ctypes.LittleEndianStructure): + _pack_ = 1 + _fields_ = [ ("used", ctypes.c_ulonglong), + ("chunk_objectid", ctypes.c_ulonglong), + ("flags", ctypes.c_ulonglong), + ] + class btrfs_ioctl_search(): def __init__(self): self.args = btrfs_ioctl_search_args() @@ -288,9 +300,102 @@ def print_file_extents(filename): float(st.st_size) / float(total_on_disk)) return 0 -if len(sys.argv) == 1: - sys.stderr.write("Usage: btrfs-debug filename ...\n") - sys.exit(1) +def print_block_groups(mountpoint): + s = btrfs_ioctl_search() + + s.args.min_type = BTRFS_BLOCK_GROUP_ITEM_KEY + s.args.max_type = BTRFS_BLOCK_GROUP_ITEM_KEY + s.args.tree_id = BTRFS_EXTENT_TREE_OBJECTID + + min_used = maxu64 + free_of_min_used = 0 + bg_of_min_used = 0 + total_free = 0 + + try: + fd = os.open(mountpoint, os.O_RDONLY) + st = os.fstat(fd) + except Exception, e: + sys.stderr.write("Failed to open %s (%s)\n" % (mountpoint, e)) + return -1 + + while True: + try: + s.search(fd) + except Exception, e: + sys.stderr.write("Search ioctl failed for %s (%s)\n" % (mountpoint, e)) + return -1 + + if s.args.nr_items == 0: + break + + # p is the results buffer from kernel + p = ctypes.addressof(s.args.buf) + header = btrfs_ioctl_search_header() + header_size = ctypes.sizeof(header) + h = ctypes.addressof(header) + p_left = args_buffer_size + + for x in xrange(0, s.args.nr_items): + # for each itme, copy the header from the buffer into + # our header struct + ctypes.memmove(h, p, header_size) + p += header_size + p_left -= header_size + + # this would be a kernel bug it shouldn't be sending malformed + # items + if p_left <= 0: + break + + if header.type == BTRFS_BLOCK_GROUP_ITEM_KEY: + bg = btrfs_block_group_item() + + # this would be a kernel bug + if p_left < ctypes.sizeof(bg): + break + + ctypes.memmove(ctypes.addressof(bg), p, ctypes.sizeof(bg)) + if bg.flags & BTRFS_BLOCK_GROUP_DATA: + print "block group offset %Lu len %Lu used %Lu chunk_objectid %Lu flags %Lu usage %.2f" %\ + (header.objectid, header.offset, bg.used, bg.chunk_objectid, bg.flags, float(bg.used) / float(header.offset)) + + total_free += (header.offset - bg.used) + if min_used >= bg.used: + min_used = bg.used + free_of_min_used = (header.offset - bg.used) + bg_of_min_used = header.objectid + + p += header.len + p_left -= header.len + if p_left <= 0: + break + + s.args.min_objectid = header.objectid + + if s.args.min_objectid < maxu64: + s.args.min_objectid += 1 + if s.args.min_objectid > s.args.max_objectid: + break + + print "total_free %Lu min_used %Lu free_of_min_used %Lu block_group_of_min_used %Lu" %\ + (total_free, min_used, free_of_min_used, bg_of_min_used) + if (total_free - free_of_min_used) >= min_used: + print "balance block group (%Lu) can reduce the number of data block group" % bg_of_min_used + + return 0 + +# main +parser = argparse.ArgumentParser() +parser.add_argument('path', nargs='+') +parser.add_argument('-b', '--block-group', action='store_const', const=1, help='get block group information, use mountpoint as "path"') +parser.add_argument('-f', '--file', action='store_const', const=1, help='get file mapping, use filepath') + +args = parser.parse_args() -for f in sys.argv[1:]: - print_file_extents(f) +if args.block_group: + for i in args.path[0:]: + print_block_groups(i) +elif args.file: + for f in args.path[0:]: + print_file_extents(f) -- cgit v1.2.3