Stability | provisional |
---|---|
Portability | non-portable (requires Linux) |
Safe Haskell | Safe |
Language | Haskell2010 |
System.Linux.FileExtents
Description
This module can be used to retrieve information about how a particular file is stored on disk (i.e. the file fragmentation). It accomplishes that by directly calling the FIEMAP ioctl provided by recent versions of the Linux kernel. This ioctl is specific to Linux and therefore this module is not portable.
For more information about the FIEMAP ioctl see filesystems/fiemap.txt
in the kernel documentation.
- type ExtentFlags = Word32
- efLast :: ExtentFlags
- efUnknown :: ExtentFlags
- efDelalloc :: ExtentFlags
- efEncoded :: ExtentFlags
- efDataEncrypted :: ExtentFlags
- efNotAligned :: ExtentFlags
- efDataInline :: ExtentFlags
- efDataTail :: ExtentFlags
- efUnwritten :: ExtentFlags
- efMerged :: ExtentFlags
- efShared :: ExtentFlags
- data Extent = Extent {}
- data ReqFlags = ReqFlags {}
- defReqFlags :: ReqFlags
- getExtentsFd :: ReqFlags -> Fd -> Maybe (Word64, Word64) -> IO [Extent]
- getExtents :: ReqFlags -> FilePath -> Maybe (Word64, Word64) -> IO [Extent]
- getExtentCountFd :: ReqFlags -> Fd -> Maybe (Word64, Word64) -> IO Word32
- getExtentCount :: ReqFlags -> FilePath -> Maybe (Word64, Word64) -> IO Word32
Extent flags
See filesystems/fiemap.txt
in the kernel documentation for a more
detailed description of each of these flags.
type ExtentFlags = Word32 #
efLast :: ExtentFlags #
Last extent in file.
Data location unknown.
Location still pending.
Data cannot be read while fs is unmounted.
efDataEncrypted :: ExtentFlags #
Data is encrypted by fs.
Extent offsets may not be block aligned.
Data mixed with metadata.
Multiple files in block.
Space allocated, but no data (i.e. zero).
efMerged :: ExtentFlags #
File does not natively support extents. Result merged for efficiency.
efShared :: ExtentFlags #
Space shared with other files.
Extents
Description of a single extent. All offsets and lengths are in bytes.
Constructors
Extent | |
Fields
|
Request flags
Flags the modify the behavior of extent information requests.
Constructors
ReqFlags | |
defReqFlags :: ReqFlags #
Default values for the request flags. All options are disabled.
Getting extent information
Arguments
:: ReqFlags | |
-> Fd | |
-> Maybe (Word64, Word64) | The range (offset and length) within the file to look extents for. Use |
-> IO [Extent] |
Retrieve the list of all extents associated with the file referenced by the file descriptor. Extents returned mirror those on disk - that is, the logical offset of the first returned extent may start before the requested range, and the last returned extent may end after the end of the requested range.
Note: getExtentsFd
might call the FIEMAP ioctl multiple times in order to
retrieve all the extents of the file. This is necessary when the file
has too many fragments. If the file is modified in the meantime, the
returned list might be inconsistent.
getExtents :: ReqFlags -> FilePath -> Maybe (Word64, Word64) -> IO [Extent] #
Like getExtentsFd
except that it operates on file paths instead of
file descriptors.
getExtentCountFd :: ReqFlags -> Fd -> Maybe (Word64, Word64) -> IO Word32 #
Like getExtentsFd
except that it returns the number of extents
instead of a list.
getExtentCount :: ReqFlags -> FilePath -> Maybe (Word64, Word64) -> IO Word32 #
Like getExtents
except that it returns the number of extents
instead of a list.