7869a4a6c5
Add a new fiemap flag which forces the all of the extents in an inode to be cached in the extent_status tree. This is critically important when using AIO to a preallocated file, since if we need to read in blocks from the extent tree, the io_submit(2) system call becomes synchronous, and the AIO is no longer "A", which is bad. In addition, for most files which have an external leaf tree block, the cost of caching the information in the extent status tree will be less than caching the entire 4k block in the buffer cache. So it is generally a win to keep the extent information cached. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
70 lines
2.6 KiB
C
70 lines
2.6 KiB
C
/*
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* FS_IOC_FIEMAP ioctl infrastructure.
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*
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* Some portions copyright (C) 2007 Cluster File Systems, Inc
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*
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* Authors: Mark Fasheh <mfasheh@suse.com>
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* Kalpak Shah <kalpak.shah@sun.com>
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* Andreas Dilger <adilger@sun.com>
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*/
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#ifndef _LINUX_FIEMAP_H
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#define _LINUX_FIEMAP_H
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#include <linux/types.h>
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struct fiemap_extent {
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__u64 fe_logical; /* logical offset in bytes for the start of
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* the extent from the beginning of the file */
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__u64 fe_physical; /* physical offset in bytes for the start
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* of the extent from the beginning of the disk */
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__u64 fe_length; /* length in bytes for this extent */
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__u64 fe_reserved64[2];
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__u32 fe_flags; /* FIEMAP_EXTENT_* flags for this extent */
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__u32 fe_reserved[3];
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};
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struct fiemap {
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__u64 fm_start; /* logical offset (inclusive) at
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* which to start mapping (in) */
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__u64 fm_length; /* logical length of mapping which
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* userspace wants (in) */
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__u32 fm_flags; /* FIEMAP_FLAG_* flags for request (in/out) */
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__u32 fm_mapped_extents;/* number of extents that were mapped (out) */
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__u32 fm_extent_count; /* size of fm_extents array (in) */
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__u32 fm_reserved;
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struct fiemap_extent fm_extents[0]; /* array of mapped extents (out) */
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};
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#define FIEMAP_MAX_OFFSET (~0ULL)
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#define FIEMAP_FLAG_SYNC 0x00000001 /* sync file data before map */
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#define FIEMAP_FLAG_XATTR 0x00000002 /* map extended attribute tree */
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#define FIEMAP_FLAG_CACHE 0x00000004 /* request caching of the extents */
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#define FIEMAP_FLAGS_COMPAT (FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR)
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#define FIEMAP_EXTENT_LAST 0x00000001 /* Last extent in file. */
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#define FIEMAP_EXTENT_UNKNOWN 0x00000002 /* Data location unknown. */
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#define FIEMAP_EXTENT_DELALLOC 0x00000004 /* Location still pending.
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* Sets EXTENT_UNKNOWN. */
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#define FIEMAP_EXTENT_ENCODED 0x00000008 /* Data can not be read
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* while fs is unmounted */
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#define FIEMAP_EXTENT_DATA_ENCRYPTED 0x00000080 /* Data is encrypted by fs.
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* Sets EXTENT_NO_BYPASS. */
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#define FIEMAP_EXTENT_NOT_ALIGNED 0x00000100 /* Extent offsets may not be
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* block aligned. */
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#define FIEMAP_EXTENT_DATA_INLINE 0x00000200 /* Data mixed with metadata.
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* Sets EXTENT_NOT_ALIGNED.*/
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#define FIEMAP_EXTENT_DATA_TAIL 0x00000400 /* Multiple files in block.
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* Sets EXTENT_NOT_ALIGNED.*/
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#define FIEMAP_EXTENT_UNWRITTEN 0x00000800 /* Space allocated, but
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* no data (i.e. zero). */
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#define FIEMAP_EXTENT_MERGED 0x00001000 /* File does not natively
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* support extents. Result
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* merged for efficiency. */
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#define FIEMAP_EXTENT_SHARED 0x00002000 /* Space shared with other
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* files. */
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#endif /* _LINUX_FIEMAP_H */
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