filemap: remove FilemapSeek class
FIEMAP API was added to Linux kernel 2.6.28 back in 2008 SEEK_HOLE and SEEK_DATA API was added much letter. As FIEMAP is used by filemap module as a default API it's safe to remove FileMpSeek class as it's never used. [YOCTO #10618] (From OE-Core rev: 44e9406ea6e3263d2fb95e9d534a21f74f318480) Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Ed Bartosh
Richard Purdie
parent
fae19c345d
commit
6b80c13f7a
|
|
@ -54,24 +54,46 @@ class Error(Exception):
|
|||
"""A class for all the other exceptions raised by this module."""
|
||||
pass
|
||||
|
||||
# Below goes the FIEMAP ioctl implementation, which is not very readable
|
||||
# because it deals with the rather complex FIEMAP ioctl. To understand the
|
||||
# code, you need to know the FIEMAP interface, which is documented in the
|
||||
# "Documentation/filesystems/fiemap.txt" file in the Linux kernel sources.
|
||||
|
||||
class _FilemapBase(object):
|
||||
# Format string for 'struct fiemap'
|
||||
_FIEMAP_FORMAT = "=QQLLLL"
|
||||
# sizeof(struct fiemap)
|
||||
_FIEMAP_SIZE = struct.calcsize(_FIEMAP_FORMAT)
|
||||
# Format string for 'struct fiemap_extent'
|
||||
_FIEMAP_EXTENT_FORMAT = "=QQQQQLLLL"
|
||||
# sizeof(struct fiemap_extent)
|
||||
_FIEMAP_EXTENT_SIZE = struct.calcsize(_FIEMAP_EXTENT_FORMAT)
|
||||
# The FIEMAP ioctl number
|
||||
_FIEMAP_IOCTL = 0xC020660B
|
||||
# This FIEMAP ioctl flag which instructs the kernel to sync the file before
|
||||
# reading the block map
|
||||
_FIEMAP_FLAG_SYNC = 0x00000001
|
||||
# Size of the buffer for 'struct fiemap_extent' elements which will be used
|
||||
# when invoking the FIEMAP ioctl. The larger is the buffer, the less times the
|
||||
# FIEMAP ioctl will be invoked.
|
||||
_FIEMAP_BUFFER_SIZE = 256 * 1024
|
||||
|
||||
class FilemapFiemap:
|
||||
"""
|
||||
This is a base class for a couple of other classes in this module. This
|
||||
class simply performs the common parts of the initialization process: opens
|
||||
the image file, gets its size, etc. The 'log' parameter is the logger object
|
||||
to use for printing messages.
|
||||
This class provides API to the FIEMAP ioctl. Namely, it allows to iterate
|
||||
over all mapped blocks and over all holes.
|
||||
|
||||
This class synchronizes the image file every time it invokes the FIEMAP
|
||||
ioctl in order to work-around early FIEMAP implementation kernel bugs.
|
||||
"""
|
||||
|
||||
def __init__(self, image, log=None):
|
||||
def __init__(self, image):
|
||||
"""
|
||||
Initialize a class instance. The 'image' argument is full path to the
|
||||
file or file object to operate on.
|
||||
Initialize a class instance. The 'image' argument is full the file
|
||||
object to operate on.
|
||||
"""
|
||||
self._log = logging.getLogger(__name__)
|
||||
|
||||
self._log = log
|
||||
if self._log is None:
|
||||
self._log = logging.getLogger(__name__)
|
||||
self._log.debug("FilemapFiemap: initializing")
|
||||
|
||||
self._f_image_needs_close = False
|
||||
|
||||
|
|
@ -113,240 +135,6 @@ class _FilemapBase(object):
|
|||
self._log.debug("block size %d, blocks count %d, image size %d"
|
||||
% (self.block_size, self.blocks_cnt, self.image_size))
|
||||
|
||||
def __del__(self):
|
||||
"""The class destructor which just closes the image file."""
|
||||
if self._f_image_needs_close:
|
||||
self._f_image.close()
|
||||
|
||||
def _open_image_file(self):
|
||||
"""Open the image file."""
|
||||
try:
|
||||
self._f_image = open(self._image_path, 'rb')
|
||||
except IOError as err:
|
||||
raise Error("cannot open image file '%s': %s"
|
||||
% (self._image_path, err))
|
||||
|
||||
self._f_image_needs_close = True
|
||||
|
||||
def block_is_mapped(self, block): # pylint: disable=W0613,R0201
|
||||
"""
|
||||
This method has has to be implemented by child classes. It returns
|
||||
'True' if block number 'block' of the image file is mapped and 'False'
|
||||
otherwise.
|
||||
"""
|
||||
|
||||
raise Error("the method is not implemented")
|
||||
|
||||
def block_is_unmapped(self, block): # pylint: disable=W0613,R0201
|
||||
"""
|
||||
This method has has to be implemented by child classes. It returns
|
||||
'True' if block number 'block' of the image file is not mapped (hole)
|
||||
and 'False' otherwise.
|
||||
"""
|
||||
|
||||
raise Error("the method is not implemented")
|
||||
|
||||
def get_mapped_ranges(self, start, count): # pylint: disable=W0613,R0201
|
||||
"""
|
||||
This method has has to be implemented by child classes. This is a
|
||||
generator which yields ranges of mapped blocks in the file. The ranges
|
||||
are tuples of 2 elements: [first, last], where 'first' is the first
|
||||
mapped block and 'last' is the last mapped block.
|
||||
|
||||
The ranges are yielded for the area of the file of size 'count' blocks,
|
||||
starting from block 'start'.
|
||||
"""
|
||||
|
||||
raise Error("the method is not implemented")
|
||||
|
||||
def get_unmapped_ranges(self, start, count): # pylint: disable=W0613,R0201
|
||||
"""
|
||||
This method has has to be implemented by child classes. Just like
|
||||
'get_mapped_ranges()', but yields unmapped block ranges instead
|
||||
(holes).
|
||||
"""
|
||||
|
||||
raise Error("the method is not implemented")
|
||||
|
||||
|
||||
# The 'SEEK_HOLE' and 'SEEK_DATA' options of the file seek system call
|
||||
_SEEK_DATA = 3
|
||||
_SEEK_HOLE = 4
|
||||
|
||||
def _lseek(file_obj, offset, whence):
|
||||
"""This is a helper function which invokes 'os.lseek' for file object
|
||||
'file_obj' and with specified 'offset' and 'whence'. The 'whence'
|
||||
argument is supposed to be either '_SEEK_DATA' or '_SEEK_HOLE'. When
|
||||
there is no more data or hole starting from 'offset', this function
|
||||
returns '-1'. Otherwise the data or hole position is returned."""
|
||||
|
||||
try:
|
||||
return os.lseek(file_obj.fileno(), offset, whence)
|
||||
except OSError as err:
|
||||
# The 'lseek' system call returns the ENXIO if there is no data or
|
||||
# hole starting from the specified offset.
|
||||
if err.errno == os.errno.ENXIO:
|
||||
return -1
|
||||
elif err.errno == os.errno.EINVAL:
|
||||
raise ErrorNotSupp("the kernel or file-system does not support "
|
||||
"\"SEEK_HOLE\" and \"SEEK_DATA\"")
|
||||
else:
|
||||
raise
|
||||
|
||||
class FilemapSeek(_FilemapBase):
|
||||
"""
|
||||
This class uses the 'SEEK_HOLE' and 'SEEK_DATA' to find file block mapping.
|
||||
Unfortunately, the current implementation requires the caller to have write
|
||||
access to the image file.
|
||||
"""
|
||||
|
||||
def __init__(self, image, log=None):
|
||||
"""Refer the '_FilemapBase' class for the documentation."""
|
||||
|
||||
# Call the base class constructor first
|
||||
_FilemapBase.__init__(self, image, log)
|
||||
self._log.debug("FilemapSeek: initializing")
|
||||
|
||||
self._probe_seek_hole()
|
||||
|
||||
def _probe_seek_hole(self):
|
||||
"""
|
||||
Check whether the system implements 'SEEK_HOLE' and 'SEEK_DATA'.
|
||||
Unfortunately, there seems to be no clean way for detecting this,
|
||||
because often the system just fakes them by just assuming that all
|
||||
files are fully mapped, so 'SEEK_HOLE' always returns EOF and
|
||||
'SEEK_DATA' always returns the requested offset.
|
||||
|
||||
I could not invent a better way of detecting the fake 'SEEK_HOLE'
|
||||
implementation than just to create a temporary file in the same
|
||||
directory where the image file resides. It would be nice to change this
|
||||
to something better.
|
||||
"""
|
||||
|
||||
directory = os.path.dirname(self._image_path)
|
||||
|
||||
try:
|
||||
tmp_obj = tempfile.TemporaryFile("w+", dir=directory)
|
||||
except IOError as err:
|
||||
raise ErrorNotSupp("cannot create a temporary in \"%s\": %s"
|
||||
% (directory, err))
|
||||
|
||||
try:
|
||||
os.ftruncate(tmp_obj.fileno(), self.block_size)
|
||||
except OSError as err:
|
||||
raise ErrorNotSupp("cannot truncate temporary file in \"%s\": %s"
|
||||
% (directory, err))
|
||||
|
||||
offs = _lseek(tmp_obj, 0, _SEEK_HOLE)
|
||||
if offs != 0:
|
||||
# We are dealing with the stub 'SEEK_HOLE' implementation which
|
||||
# always returns EOF.
|
||||
self._log.debug("lseek(0, SEEK_HOLE) returned %d" % offs)
|
||||
raise ErrorNotSupp("the file-system does not support "
|
||||
"\"SEEK_HOLE\" and \"SEEK_DATA\" but only "
|
||||
"provides a stub implementation")
|
||||
|
||||
tmp_obj.close()
|
||||
|
||||
def block_is_mapped(self, block):
|
||||
"""Refer the '_FilemapBase' class for the documentation."""
|
||||
offs = _lseek(self._f_image, block * self.block_size, _SEEK_DATA)
|
||||
if offs == -1:
|
||||
result = False
|
||||
else:
|
||||
result = (offs // self.block_size == block)
|
||||
|
||||
self._log.debug("FilemapSeek: block_is_mapped(%d) returns %s"
|
||||
% (block, result))
|
||||
return result
|
||||
|
||||
def block_is_unmapped(self, block):
|
||||
"""Refer the '_FilemapBase' class for the documentation."""
|
||||
return not self.block_is_mapped(block)
|
||||
|
||||
def _get_ranges(self, start, count, whence1, whence2):
|
||||
"""
|
||||
This function implements 'get_mapped_ranges()' and
|
||||
'get_unmapped_ranges()' depending on what is passed in the 'whence1'
|
||||
and 'whence2' arguments.
|
||||
"""
|
||||
|
||||
assert whence1 != whence2
|
||||
end = start * self.block_size
|
||||
limit = end + count * self.block_size
|
||||
|
||||
while True:
|
||||
start = _lseek(self._f_image, end, whence1)
|
||||
if start == -1 or start >= limit or start == self.image_size:
|
||||
break
|
||||
|
||||
end = _lseek(self._f_image, start, whence2)
|
||||
if end == -1 or end == self.image_size:
|
||||
end = self.blocks_cnt * self.block_size
|
||||
if end > limit:
|
||||
end = limit
|
||||
|
||||
start_blk = start // self.block_size
|
||||
end_blk = end // self.block_size - 1
|
||||
self._log.debug("FilemapSeek: yielding range (%d, %d)"
|
||||
% (start_blk, end_blk))
|
||||
yield (start_blk, end_blk)
|
||||
|
||||
def get_mapped_ranges(self, start, count):
|
||||
"""Refer the '_FilemapBase' class for the documentation."""
|
||||
self._log.debug("FilemapSeek: get_mapped_ranges(%d, %d(%d))"
|
||||
% (start, count, start + count - 1))
|
||||
return self._get_ranges(start, count, _SEEK_DATA, _SEEK_HOLE)
|
||||
|
||||
def get_unmapped_ranges(self, start, count):
|
||||
"""Refer the '_FilemapBase' class for the documentation."""
|
||||
self._log.debug("FilemapSeek: get_unmapped_ranges(%d, %d(%d))"
|
||||
% (start, count, start + count - 1))
|
||||
return self._get_ranges(start, count, _SEEK_HOLE, _SEEK_DATA)
|
||||
|
||||
|
||||
# Below goes the FIEMAP ioctl implementation, which is not very readable
|
||||
# because it deals with the rather complex FIEMAP ioctl. To understand the
|
||||
# code, you need to know the FIEMAP interface, which is documented in the
|
||||
# "Documentation/filesystems/fiemap.txt" file in the Linux kernel sources.
|
||||
|
||||
# Format string for 'struct fiemap'
|
||||
_FIEMAP_FORMAT = "=QQLLLL"
|
||||
# sizeof(struct fiemap)
|
||||
_FIEMAP_SIZE = struct.calcsize(_FIEMAP_FORMAT)
|
||||
# Format string for 'struct fiemap_extent'
|
||||
_FIEMAP_EXTENT_FORMAT = "=QQQQQLLLL"
|
||||
# sizeof(struct fiemap_extent)
|
||||
_FIEMAP_EXTENT_SIZE = struct.calcsize(_FIEMAP_EXTENT_FORMAT)
|
||||
# The FIEMAP ioctl number
|
||||
_FIEMAP_IOCTL = 0xC020660B
|
||||
# This FIEMAP ioctl flag which instructs the kernel to sync the file before
|
||||
# reading the block map
|
||||
_FIEMAP_FLAG_SYNC = 0x00000001
|
||||
# Size of the buffer for 'struct fiemap_extent' elements which will be used
|
||||
# when invoking the FIEMAP ioctl. The larger is the buffer, the less times the
|
||||
# FIEMAP ioctl will be invoked.
|
||||
_FIEMAP_BUFFER_SIZE = 256 * 1024
|
||||
|
||||
class FilemapFiemap(_FilemapBase):
|
||||
"""
|
||||
This class provides API to the FIEMAP ioctl. Namely, it allows to iterate
|
||||
over all mapped blocks and over all holes.
|
||||
|
||||
This class synchronizes the image file every time it invokes the FIEMAP
|
||||
ioctl in order to work-around early FIEMAP implementation kernel bugs.
|
||||
"""
|
||||
|
||||
def __init__(self, image, log=None):
|
||||
"""
|
||||
Initialize a class instance. The 'image' argument is full the file
|
||||
object to operate on.
|
||||
"""
|
||||
|
||||
# Call the base class constructor first
|
||||
_FilemapBase.__init__(self, image, log)
|
||||
self._log.debug("FilemapFiemap: initializing")
|
||||
|
||||
self._buf_size = _FIEMAP_BUFFER_SIZE
|
||||
|
||||
# Calculate how many 'struct fiemap_extent' elements fit the buffer
|
||||
|
|
@ -362,6 +150,21 @@ class FilemapFiemap(_FilemapBase):
|
|||
# Check if the FIEMAP ioctl is supported
|
||||
self.block_is_mapped(0)
|
||||
|
||||
def __del__(self):
|
||||
"""The class destructor which just closes the image file."""
|
||||
if self._f_image_needs_close:
|
||||
self._f_image.close()
|
||||
|
||||
def _open_image_file(self):
|
||||
"""Open the image file."""
|
||||
try:
|
||||
self._f_image = open(self._image_path, 'rb')
|
||||
except IOError as err:
|
||||
raise Error("cannot open image file '%s': %s"
|
||||
% (self._image_path, err))
|
||||
|
||||
self._f_image_needs_close = True
|
||||
|
||||
def _invoke_fiemap(self, block, count):
|
||||
"""
|
||||
Invoke the FIEMAP ioctl for 'count' blocks of the file starting from
|
||||
|
|
@ -515,24 +318,10 @@ class FilemapFiemap(_FilemapBase):
|
|||
% (hole_first, start + count - 1))
|
||||
yield (hole_first, start + count - 1)
|
||||
|
||||
def filemap(image, log=None):
|
||||
"""
|
||||
Create and return an instance of a Filemap class - 'FilemapFiemap' or
|
||||
'FilemapSeek', depending on what the system we run on supports. If the
|
||||
FIEMAP ioctl is supported, an instance of the 'FilemapFiemap' class is
|
||||
returned. Otherwise, if 'SEEK_HOLE' is supported an instance of the
|
||||
'FilemapSeek' class is returned. If none of these are supported, the
|
||||
function generates an 'Error' type exception.
|
||||
"""
|
||||
|
||||
try:
|
||||
return FilemapFiemap(image, log)
|
||||
except ErrorNotSupp:
|
||||
return FilemapSeek(image, log)
|
||||
|
||||
def sparse_copy(src_fname, dst_fname, offset=0, skip=0):
|
||||
"""Efficiently copy sparse file to or into another file."""
|
||||
fmap = filemap(src_fname)
|
||||
fmap = FilemapFiemap(src_fname)
|
||||
try:
|
||||
dst_file = open(dst_fname, 'r+b')
|
||||
except IOError:
|
||||
|
|
|
|||
Loading…
Reference in New Issue