47,11 → 47,16 |
#include <futex.h> |
#include <as.h> |
#include <libadt/list.h> |
#include <assert.h> |
#include "vfs.h" |
|
atomic_t fs_head_futex = FUTEX_INITIALIZER; |
link_t fs_head; |
|
atomic_t fs_handle_next = { |
.count = 1 |
}; |
|
/** Verify the VFS info structure. |
* |
* @param info Info structure to be verified. |
305,13 → 310,80 |
|
/* |
* That was it. The FS has been registered. |
* In reply to the VFS_REGISTER request, we assign the client file |
* system a global file system handle. |
*/ |
ipc_answer_fast(rid, EOK, 0, 0); |
dprintf("\"%s\" filesystem successfully registered.\n", |
fs_info->vfs_info.name); |
fs_info->fs_handle = (int) atomic_postinc(&fs_handle_next); |
ipc_answer_fast(rid, EOK, (ipcarg_t) fs_info->fs_handle, 0); |
dprintf("\"%s\" filesystem successfully registered, handle=%d.\n", |
fs_info->vfs_info.name, fs_info->fs_handle); |
|
} |
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/** For a given file system handle, implement policy for allocating a phone. |
* |
* @param handle File system handle. |
* |
* @return Phone over which a multi-call request can be safely |
* sent. Return 0 if no phone was found. |
*/ |
int vfs_grab_phone(int handle) |
{ |
/* |
* For now, we don't try to be very clever and very fast. |
* We simply lookup the phone in the fs_head list. We currently don't |
* open any additional phones (even though that itself would be pretty |
* straightforward; housekeeping multiple open phones to a FS task would |
* be more demanding). Instead, we simply take the respective |
* phone_futex and keep it until vfs_release_phone(). |
*/ |
futex_down(&fs_head_futex); |
link_t *cur; |
fs_info_t *fs; |
for (cur = fs_head.next; cur != &fs_head; cur = cur->next) { |
fs = list_get_instance(cur, fs_info_t, fs_link); |
if (fs->fs_handle == handle) { |
futex_up(&fs_head_futex); |
/* |
* For now, take the futex unconditionally. |
* Oh yeah, serialization rocks. |
* It will be up'ed in vfs_release_phone(). |
*/ |
futex_down(&fs->phone_futex); |
return fs->phone; |
} |
} |
futex_up(&fs_head_futex); |
return 0; |
} |
|
/** Tell VFS that the phone is in use for any request. |
* |
* @param phone Phone to FS task. |
*/ |
void vfs_release_phone(int phone) |
{ |
bool found = false; |
|
futex_down(&fs_head_futex); |
link_t *cur; |
for (cur = fs_head.next; cur != &fs_head; cur = cur->next) { |
fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link); |
if (fs->phone == phone) { |
found = true; |
futex_up(&fs_head_futex); |
futex_up(&fs->phone_futex); |
return; |
} |
} |
futex_up(&fs_head_futex); |
|
/* |
* Not good to get here. |
*/ |
assert(found == true); |
} |
|
/** |
* @} |
*/ |