On Tue, Nov 13, 2007 at 02:30:02AM +0530, Kalpak Shah wrote:
> Recently there was discussion about an "FIle Extent MAP"(FIEMAP) ioctl for
> efficiently mapping the extents and holes of a file. This will be many
> times more efficient than FIBMAP by cutting down the number of ioctls.
Thanks for sending this out.
> This patch adds the FIEMAP header file in include/linux.
Any problem with defining the IOC_FIEMAP ioctl number in this header too? No
EXT4 prefix so we keep things generic too, please.
--Mark
> Signed-off-by: Andreas Dilger <adilger@xxxxxxx>
> Signed-off-by: Kalpak Shah <kalpak.shah@xxxxxxx>
>
> Index: linux-2.6.23.1/include/linux/fiemap.h
> ===================================================================
> --- /dev/null
> +++ linux-2.6.23.1/include/linux/fiemap.h
> @@ -0,0 +1,49 @@
> +/*
> + * include/linux/fiemap.h
> + *
> + * Copyright (C) 2007 Sun Microsystems, Inc.
> + *
> + * Author: Kalpak Shah <kalpak.shah@xxxxxxx>
> + * Andreas Dilger <adilger@xxxxxxx>
> + */
> +
> +#ifndef _LINUX_FIEMAP_H
> +#define _LINUX_FIEMAP_H
> +
> +struct fiemap_extent {
> + __u64 fe_offset; /* offset in bytes for the start of the extent */
> + __u64 fe_length; /* length in bytes for the extent */
> + __u32 fe_flags; /* returned FIEMAP_EXTENT_* flags for the extent */
> + __u32 fe_lun; /* logical device number for extent (starting at 0)*/
> +};
> +
> +struct fiemap {
> + __u64 fm_start; /* logical starting byte offset (in/out) */
> + __u64 fm_length; /* logical length of map (in/out) */
> + __u32 fm_flags; /* FIEMAP_FLAG_* flags for request (in/out) */
> + __u32 fm_extent_count; /* number of extents in fm_extents (in/out) */
> + __u64 fm_end_offset; /* logical offset of end of mapping in last ioctl */
> + struct fiemap_extent fm_extents[0];
> +};
> +
> +#define FIEMAP_FLAG_SYNC 0x00000001 /* sync file data before map */
> +#define FIEMAP_FLAG_HSM_READ 0x00000002 /* get data from HSM before map */
> +#define FIEMAP_FLAG_NUM_EXTENTS 0x00000004 /* return only number of extents */
> +#define FIEMAP_FLAG_INCOMPAT 0xff000000 /* error for unknown flags in here */
> +
> +#define FIEMAP_FLAG_LUN_OFFSET 0x01000000 /* use lun offsets, instead of
> + * logical file offsets */
> +
> +#define FIEMAP_EXTENT_HOLE 0x00000001 /* has no data or space allocation */
> +#define FIEMAP_EXTENT_UNWRITTEN 0x00000002 /* space allocated, but no data */
> +#define FIEMAP_EXTENT_UNMAPPED 0x00000004 /* has data but no space allocation*/
> +#define FIEMAP_EXTENT_ERROR 0x00000008 /* mapping error, errno in fe_start*/
> +#define FIEMAP_EXTENT_NO_DIRECT 0x00000010 /* cannot access data directly */
> +#define FIEMAP_EXTENT_LAST 0x00000020 /* last extent in the file */
> +#define FIEMAP_EXTENT_DELALLOC 0x00000040 /* has data but not yet written,
> + * must have EXTENT_UNKNOWN set */
> +#define FIEMAP_EXTENT_SECONDARY 0x00000080 /* data (also) in secondary storage,
> + * not in primary if EXTENT_UNKNOWN*/
> +#define FIEMAP_EXTENT_EOF 0x00000100 /* if fm_start+fm_len is beyond EOF*/
> +
> +#endif /* _LINUX_FIEMAP_H */
>
--
Mark Fasheh
Senior Software Developer, Oracle
mark.fasheh@xxxxxxxxxx
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