hw/9pfs/coth.h

   1 /*
   2  * 9p backend
   3  *
   4  * Copyright IBM, Corp. 2010
   5  *
   6  * Authors:
   7  *  Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
   8  *  Venkateswararao Jujjuri(JV) <jvrao@linux.vnet.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2.  See
  11  * the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #ifndef QEMU_9P_COTH_H
  16 #define QEMU_9P_COTH_H
  17
  18 #include "qemu/thread.h"
  19 #include "qemu/coroutine.h"
  20 #include "9p.h"
  21
  22 /*
  23  * we want to use bottom half because we want to make sure the below
  24  * sequence of events.
  25  *
  26  *   1. Yield the coroutine in the QEMU thread.
  27  *   2. Submit the coroutine to a worker thread.
  28  *   3. Enter the coroutine in the worker thread.
  29  * we cannot swap step 1 and 2, because that would imply worker thread
  30  * can enter coroutine while step1 is still running
  31  *
  32  * PERFORMANCE CONSIDERATIONS: As a rule of thumb, keep in mind
  33  * that hopping between threads adds @b latency! So when handling a
  34  * 9pfs request, avoid calling v9fs_co_run_in_worker() too often, because
  35  * this might otherwise sum up to a significant, huge overall latency for
  36  * providing the response for just a single request. For that reason it
  37  * is highly recommended to fetch all data from fs driver with a single
  38  * fs driver request on a background I/O thread (bottom half) in one rush
  39  * first and then eventually assembling the final response from that data
  40  * on main I/O thread (top half).
  41  */
  42 #define v9fs_co_run_in_worker(code_block)                               \
  43     do {                                                                \
  44         QEMUBH *co_bh;                                                  \
  45         co_bh = qemu_bh_new(co_run_in_worker_bh,                        \
  46                             qemu_coroutine_self());                     \
  47         qemu_bh_schedule(co_bh);                                        \
  48         /*                                                              \
  49          * yield in qemu thread and re-enter back                       \
  50          * in worker thread                                             \
  51          */                                                             \
  52         qemu_coroutine_yield();                                         \
  53         qemu_bh_delete(co_bh);                                          \
  54         do {                                                            \
  55             code_block;                                                 \
  56         } while (0);                                                    \
  57         /* re-enter back to qemu thread */                              \
  58         qemu_coroutine_yield();                                         \
  59     } while (0)
  60
  61 void co_run_in_worker_bh(void *);
  62 int coroutine_fn v9fs_co_readlink(V9fsPDU *, V9fsPath *, V9fsString *);
  63 int coroutine_fn v9fs_co_readdir(V9fsPDU *, V9fsFidState *, struct dirent **);
  64 int coroutine_fn v9fs_co_readdir_many(V9fsPDU *, V9fsFidState *,
  65                                       struct V9fsDirEnt **, off_t, int32_t,
  66                                       bool);
  67 off_t coroutine_fn v9fs_co_telldir(V9fsPDU *, V9fsFidState *);
  68 void coroutine_fn v9fs_co_seekdir(V9fsPDU *, V9fsFidState *, off_t);
  69 void coroutine_fn v9fs_co_rewinddir(V9fsPDU *, V9fsFidState *);
  70 int coroutine_fn v9fs_co_statfs(V9fsPDU *, V9fsPath *, struct statfs *);
  71 int coroutine_fn v9fs_co_lstat(V9fsPDU *, V9fsPath *, struct stat *);
  72 int coroutine_fn v9fs_co_chmod(V9fsPDU *, V9fsPath *, mode_t);
  73 int coroutine_fn v9fs_co_utimensat(V9fsPDU *, V9fsPath *, struct timespec [2]);
  74 int coroutine_fn v9fs_co_chown(V9fsPDU *, V9fsPath *, uid_t, gid_t);
  75 int coroutine_fn v9fs_co_truncate(V9fsPDU *, V9fsPath *, off_t);
  76 int coroutine_fn v9fs_co_llistxattr(V9fsPDU *, V9fsPath *, void *, size_t);
  77 int coroutine_fn v9fs_co_lgetxattr(V9fsPDU *, V9fsPath *,
  78                                    V9fsString *, void *, size_t);
  79 int coroutine_fn v9fs_co_mknod(V9fsPDU *, V9fsFidState *, V9fsString *, uid_t,
  80                                gid_t, dev_t, mode_t, struct stat *);
  81 int coroutine_fn v9fs_co_mkdir(V9fsPDU *, V9fsFidState *, V9fsString *,
  82                                mode_t, uid_t, gid_t, struct stat *);
  83 int coroutine_fn v9fs_co_remove(V9fsPDU *, V9fsPath *);
  84 int coroutine_fn v9fs_co_rename(V9fsPDU *, V9fsPath *, V9fsPath *);
  85 int coroutine_fn v9fs_co_unlinkat(V9fsPDU *, V9fsPath *, V9fsString *,
  86                                   int flags);
  87 int coroutine_fn v9fs_co_renameat(V9fsPDU *, V9fsPath *, V9fsString *,
  88                                   V9fsPath *, V9fsString *);
  89 int coroutine_fn v9fs_co_fstat(V9fsPDU *, V9fsFidState *, struct stat *);
  90 int coroutine_fn v9fs_co_opendir(V9fsPDU *, V9fsFidState *);
  91 int coroutine_fn v9fs_co_open(V9fsPDU *, V9fsFidState *, int);
  92 int coroutine_fn v9fs_co_open2(V9fsPDU *, V9fsFidState *, V9fsString *,
  93                                gid_t, int, int, struct stat *);
  94 int coroutine_fn v9fs_co_lsetxattr(V9fsPDU *, V9fsPath *, V9fsString *,
  95                                    void *, size_t, int);
  96 int coroutine_fn v9fs_co_lremovexattr(V9fsPDU *, V9fsPath *, V9fsString *);
  97 int coroutine_fn v9fs_co_closedir(V9fsPDU *, V9fsFidOpenState *);
  98 int coroutine_fn v9fs_co_close(V9fsPDU *, V9fsFidOpenState *);
  99 int coroutine_fn v9fs_co_fsync(V9fsPDU *, V9fsFidState *, int);
 100 int coroutine_fn v9fs_co_symlink(V9fsPDU *, V9fsFidState *, V9fsString *,
 101                                  const char *, gid_t, struct stat *);
 102 int coroutine_fn v9fs_co_link(V9fsPDU *, V9fsFidState *,
 103                               V9fsFidState *, V9fsString *);
 104 int coroutine_fn v9fs_co_pwritev(V9fsPDU *, V9fsFidState *,
 105                                  struct iovec *, int, int64_t);
 106 int coroutine_fn v9fs_co_preadv(V9fsPDU *, V9fsFidState *,
 107                                 struct iovec *, int, int64_t);
 108 int coroutine_fn v9fs_co_name_to_path(V9fsPDU *, V9fsPath *,
 109                                       const char *, V9fsPath *);
 110 int coroutine_fn v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t,
 111                                 V9fsStatDotl *v9stat);
 112
 113 #endif