mirror of
https://github.com/kdave/btrfs-progs
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05063de62c
This is a starting point for a debugfs style python interface using the search ioctl. For now it can only do one thing, which is to print out all the extents in a file and calculate the compression ratio. Over time it will grow more features, especially for the kinds of things we might run btrfs-debug-tree to find out. Expect the usage and output to change dramatically over time (don't hard code to it). Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: David Sterba <dsterba@suse.cz>
297 lines
9.3 KiB
Python
Executable File
297 lines
9.3 KiB
Python
Executable File
#!/usr/bin/env python2
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#
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# Simple python program to print out all the extents of a single file
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# LGPLv2 license
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# Copyright Facebook 2014
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import sys,os,struct,fcntl,ctypes,stat
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# helpers for max ints
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maxu64 = (1L << 64) - 1
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maxu32 = (1L << 32) - 1
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# the inode (like form stat)
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BTRFS_INODE_ITEM_KEY = 1
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# backref to the directory
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BTRFS_INODE_REF_KEY = 12
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# backref to the directory v2
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BTRFS_INODE_EXTREF_KEY = 13
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# xattr items
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BTRFS_XATTR_ITEM_KEY = 24
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# orphans for list files
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BTRFS_ORPHAN_ITEM_KEY = 48
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# treelog items for dirs
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BTRFS_DIR_LOG_ITEM_KEY = 60
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BTRFS_DIR_LOG_INDEX_KEY = 72
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# dir items and dir indexes both hold filenames
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BTRFS_DIR_ITEM_KEY = 84
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BTRFS_DIR_INDEX_KEY = 96
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# these are the file extent pointers
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BTRFS_EXTENT_DATA_KEY = 108
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# csums
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BTRFS_EXTENT_CSUM_KEY = 128
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# root item for subvols and snapshots
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BTRFS_ROOT_ITEM_KEY = 132
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# root item backrefs
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BTRFS_ROOT_BACKREF_KEY = 144
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BTRFS_ROOT_REF_KEY = 156
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# each allocated extent has an extent item
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BTRFS_EXTENT_ITEM_KEY = 168
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# optimized extents for metadata only
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BTRFS_METADATA_ITEM_KEY = 169
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# backrefs for extents
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BTRFS_TREE_BLOCK_REF_KEY = 176
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BTRFS_EXTENT_DATA_REF_KEY = 178
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BTRFS_EXTENT_REF_V0_KEY = 180
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BTRFS_SHARED_BLOCK_REF_KEY = 182
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BTRFS_SHARED_DATA_REF_KEY = 184
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# one of these for each block group
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BTRFS_BLOCK_GROUP_ITEM_KEY = 192
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# dev extents records which part of each device is allocated
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BTRFS_DEV_EXTENT_KEY = 204
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# dev items describe devs
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BTRFS_DEV_ITEM_KEY = 216
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# one for each chunk
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BTRFS_CHUNK_ITEM_KEY = 228
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# qgroup info
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BTRFS_QGROUP_STATUS_KEY = 240
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BTRFS_QGROUP_INFO_KEY = 242
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BTRFS_QGROUP_LIMIT_KEY = 244
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BTRFS_QGROUP_RELATION_KEY = 246
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# records balance progress
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BTRFS_BALANCE_ITEM_KEY = 248
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# stats on device errors
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BTRFS_DEV_STATS_KEY = 249
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BTRFS_DEV_REPLACE_KEY = 250
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BTRFS_STRING_ITEM_KEY = 253
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# in the kernel sources, this is flattened
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# btrfs_ioctl_search_args_v2. It includes both the btrfs_ioctl_search_key
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# and the buffer. We're using a 64K buffer size.
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#
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args_buffer_size = 65536
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class btrfs_ioctl_search_args(ctypes.Structure):
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_pack_ = 1
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_fields_ = [ ("tree_id", ctypes.c_ulonglong),
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("min_objectid", ctypes.c_ulonglong),
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("max_objectid", ctypes.c_ulonglong),
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("min_offset", ctypes.c_ulonglong),
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("max_offset", ctypes.c_ulonglong),
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("min_transid", ctypes.c_ulonglong),
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("max_transid", ctypes.c_ulonglong),
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("min_type", ctypes.c_uint),
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("max_type", ctypes.c_uint),
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("nr_items", ctypes.c_uint),
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("unused", ctypes.c_uint),
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("unused1", ctypes.c_ulonglong),
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("unused2", ctypes.c_ulonglong),
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("unused3", ctypes.c_ulonglong),
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("unused4", ctypes.c_ulonglong),
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("buf_size", ctypes.c_ulonglong),
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("buf", ctypes.c_ubyte * args_buffer_size),
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]
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# the search ioctl resturns one header for each item
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#
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class btrfs_ioctl_search_header(ctypes.Structure):
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_pack_ = 1
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_fields_ = [ ("transid", ctypes.c_ulonglong),
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("objectid", ctypes.c_ulonglong),
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("offset", ctypes.c_ulonglong),
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("type", ctypes.c_uint),
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("len", ctypes.c_uint),
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]
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# the type field in btrfs_file_extent_item
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BTRFS_FILE_EXTENT_INLINE = 0
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BTRFS_FILE_EXTENT_REG = 1
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BTRFS_FILE_EXTENT_PREALLOC = 2
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class btrfs_file_extent_item(ctypes.LittleEndianStructure):
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_pack_ = 1
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_fields_ = [ ("generation", ctypes.c_ulonglong),
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("ram_bytes", ctypes.c_ulonglong),
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("compression", ctypes.c_ubyte),
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("encryption", ctypes.c_ubyte),
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("other_encoding", ctypes.c_ubyte * 2),
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("type", ctypes.c_ubyte),
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("disk_bytenr", ctypes.c_ulonglong),
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("disk_num_bytes", ctypes.c_ulonglong),
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("offset", ctypes.c_ulonglong),
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("num_bytes", ctypes.c_ulonglong),
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]
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class btrfs_ioctl_search():
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def __init__(self):
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self.args = btrfs_ioctl_search_args()
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self.args.tree_id = 0
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self.args.min_objectid = 0
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self.args.max_objectid = maxu64
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self.args.min_offset = 0
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self.args.max_offset = maxu64
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self.args.min_transid = 0
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self.args.max_transid = maxu64
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self.args.min_type = 0
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self.args.max_type = maxu32
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self.args.nr_items = 0
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self.args.buf_size = args_buffer_size
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# magic encoded for x86_64 this is the v2 search ioctl
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self.ioctl_num = 3228603409L
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# the results of the search get stored into args.buf
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def search(self, fd, nritems=65536):
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self.args.nr_items = nritems
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fcntl.ioctl(fd, self.ioctl_num, self.args, 1)
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# this moves the search key forward by one. If the end result is
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# still a valid search key (all mins less than all maxes), we return
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# True. Otherwise False
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#
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def advance_search(search):
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if search.args.min_offset < maxu64:
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search.args.min_offset += 1
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elif search.args.min_type < 255:
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search.args.min_type += 1
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elif search.args.min_objectid < maxu64:
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search.args.min_objectid += 1
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else:
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return False
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if search.args.min_offset > search.args.max_offset:
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return False
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if search.args.min_type > search.args.max_type:
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return False
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if search.args.min_objectid > search.args.max_objectid:
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return False
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return True
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# given one search_header and one file_item, print the details. This
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# also tosses the [disk_bytenr,disk_num_bytes] into extent_hash to record
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# which extents were used by this file
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#
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def print_one_extent(header, fi, extent_hash):
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# we're ignoring inline items for now
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if fi.type == BTRFS_FILE_EXTENT_INLINE:
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# header.len is the length of the item returned. We subtract
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# the part of the file item header that is actually used (21 bytes)
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# and we get the length of the inlined data.
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# this may or may not be compressed
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inline_len = header.len - 21
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if fi.compression:
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ram_bytes = fi.ram_bytes
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else:
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ram_bytes = inline_len
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print "(%Lu %Lu): ram %Lu disk 0 disk_size %Lu -- inline" % \
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(header.objectid, header.offset, ram_bytes, inline_len)
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extent_hash[-1] = inline_len
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return
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if fi.disk_bytenr == 0:
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tag = " -- hole"
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else:
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tag = ""
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print "(%Lu %Lu): ram %Lu disk %Lu disk_size %Lu%s" % (header.objectid,
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header.offset, fi.num_bytes, fi.disk_bytenr, fi.disk_num_bytes, tag)
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if fi.disk_bytenr:
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extent_hash[fi.disk_bytenr] = fi.disk_num_bytes
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# open 'filename' and run the search ioctl against it, printing all the extents
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# we find
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def print_file_extents(filename):
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extent_hash = {}
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s = btrfs_ioctl_search()
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s.args.min_type = BTRFS_EXTENT_DATA_KEY
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s.args.max_type = BTRFS_EXTENT_DATA_KEY
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try:
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fd = os.open(filename, os.O_RDONLY)
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st = os.fstat(fd)
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except Exception, e:
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sys.stderr.write("Failed to open %s (%s)\n" % (filename, e))
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return -1
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if not stat.S_ISREG(st.st_mode):
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sys.stderr.write("%s not a regular file\n" % filename)
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return 0
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s.args.min_objectid = st.st_ino
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s.args.max_objectid = st.st_ino
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size = st.st_size
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while True:
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try:
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s.search(fd)
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except Exception, e:
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sys.stderr.write("Search ioctl failed for %s (%s)\n" % (filename, e))
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return -1
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if s.args.nr_items == 0:
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break
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# p is the results buffer from the kernel
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p = ctypes.addressof(s.args.buf)
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header = btrfs_ioctl_search_header()
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header_size = ctypes.sizeof(header)
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h = ctypes.addressof(header)
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p_left = args_buffer_size
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for x in xrange(0, s.args.nr_items):
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# for each item, copy the header from the buffer into
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# our header struct.
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ctypes.memmove(h, p, header_size)
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p += header_size
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p_left -= header_size
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# this would be a kernel bug it shouldn't be sending malformed
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# items
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if p_left <= 0:
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break
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if header.type == BTRFS_EXTENT_DATA_KEY:
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fi = btrfs_file_extent_item()
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# this would also be a kernel bug
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if p_left < ctypes.sizeof(fi):
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break
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# Copy the file item out of the results buffer
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ctypes.memmove(ctypes.addressof(fi), p, ctypes.sizeof(fi))
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print_one_extent(header, fi, extent_hash)
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p += header.len
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p_left -= header.len
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if p_left <= 0:
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break
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s.args.min_offset = header.offset
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if not advance_search(s):
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break
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total_on_disk = 0
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total_extents = 0
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for x in extent_hash.itervalues():
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total_on_disk += x
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total_extents += 1
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# don't divide by zero
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if total_on_disk == 0:
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total_on_disk = 1
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print "file: %s extents %Lu disk size %Lu logical size %Lu ratio %.2f" % \
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(filename, total_extents, total_on_disk, st.st_size,
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float(st.st_size) / float(total_on_disk))
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return 0
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if len(sys.argv) == 1:
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sys.stderr.write("Usage: btrfs-debug filename ...\n")
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sys.exit(1)
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for f in sys.argv[1:]:
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print_file_extents(f)
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