linux/fs/ceph/ioctl.h
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   1#ifndef FS_CEPH_IOCTL_H
   2#define FS_CEPH_IOCTL_H
   3
   4#include <linux/ioctl.h>
   5#include <linux/types.h>
   6
   7#define CEPH_IOCTL_MAGIC 0x97
   8
   9/*
  10 * CEPH_IOC_GET_LAYOUT - get file layout or dir layout policy
  11 * CEPH_IOC_SET_LAYOUT - set file layout
  12 * CEPH_IOC_SET_LAYOUT_POLICY - set dir layout policy
  13 *
  14 * The file layout specifies how file data is striped over objects in
  15 * the distributed object store, which object pool they belong to (if
  16 * it differs from the default), and an optional 'preferred osd' to
  17 * store them on.
  18 *
  19 * Files get a new layout based on the policy set on the containing
  20 * directory or one of its ancestors.  The GET_LAYOUT ioctl will let
  21 * you examine the layout for a file or the policy on a directory.
  22 *
  23 * SET_LAYOUT will let you set a layout on a newly created file.  This
  24 * only works immediately after the file is created and before any
  25 * data is written to it.
  26 *
  27 * SET_LAYOUT_POLICY will let you set a layout policy (default layout)
  28 * on a directory that will apply to any new files created in that
  29 * directory (or any child directory that doesn't specify a layout of
  30 * its own).
  31 */
  32
  33/* use u64 to align sanely on all archs */
  34struct ceph_ioctl_layout {
  35        __u64 stripe_unit, stripe_count, object_size;
  36        __u64 data_pool;
  37
  38        /* obsolete.  new values ignored, always return -1 */
  39        __s64 preferred_osd;
  40};
  41
  42#define CEPH_IOC_GET_LAYOUT _IOR(CEPH_IOCTL_MAGIC, 1,           \
  43                                   struct ceph_ioctl_layout)
  44#define CEPH_IOC_SET_LAYOUT _IOW(CEPH_IOCTL_MAGIC, 2,           \
  45                                   struct ceph_ioctl_layout)
  46#define CEPH_IOC_SET_LAYOUT_POLICY _IOW(CEPH_IOCTL_MAGIC, 5,    \
  47                                   struct ceph_ioctl_layout)
  48
  49/*
  50 * CEPH_IOC_GET_DATALOC - get location of file data in the cluster
  51 *
  52 * Extract identity, address of the OSD and object storing a given
  53 * file offset.
  54 */
  55struct ceph_ioctl_dataloc {
  56        __u64 file_offset;           /* in+out: file offset */
  57        __u64 object_offset;         /* out: offset in object */
  58        __u64 object_no;             /* out: object # */
  59        __u64 object_size;           /* out: object size */
  60        char object_name[64];        /* out: object name */
  61        __u64 block_offset;          /* out: offset in block */
  62        __u64 block_size;            /* out: block length */
  63        __s64 osd;                   /* out: osd # */
  64        struct sockaddr_storage osd_addr; /* out: osd address */
  65};
  66
  67#define CEPH_IOC_GET_DATALOC _IOWR(CEPH_IOCTL_MAGIC, 3, \
  68                                   struct ceph_ioctl_dataloc)
  69
  70/*
  71 * CEPH_IOC_LAZYIO - relax consistency
  72 *
  73 * Normally Ceph switches to synchronous IO when multiple clients have
  74 * the file open (and or more for write).  Reads and writes bypass the
  75 * page cache and go directly to the OSD.  Setting this flag on a file
  76 * descriptor will allow buffered IO for this file in cases where the
  77 * application knows it won't interfere with other nodes (or doesn't
  78 * care).
  79 */
  80#define CEPH_IOC_LAZYIO _IO(CEPH_IOCTL_MAGIC, 4)
  81
  82/*
  83 * CEPH_IOC_SYNCIO - force synchronous IO
  84 *
  85 * This ioctl sets a file flag that forces the synchronous IO that
  86 * bypasses the page cache, even if it is not necessary.  This is
  87 * essentially the opposite behavior of IOC_LAZYIO.  This forces the
  88 * same read/write path as a file opened by multiple clients when one
  89 * or more of those clients is opened for write.
  90 *
  91 * Note that this type of sync IO takes a different path than a file
  92 * opened with O_SYNC/D_SYNC (writes hit the page cache and are
  93 * immediately flushed on page boundaries).  It is very similar to
  94 * O_DIRECT (writes bypass the page cache) excep that O_DIRECT writes
  95 * are not copied (user page must remain stable) and O_DIRECT writes
  96 * have alignment restrictions (on the buffer and file offset).
  97 */
  98#define CEPH_IOC_SYNCIO _IO(CEPH_IOCTL_MAGIC, 5)
  99
 100#endif
 101
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