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Replaced fs_mount::covers_vnode by Vnode::covers 

Introduce a Vnode::covers field. It is currently only used for the root
node of an fs_mount, replacing fs_mount::covers_vnode.
This commit is contained in:
Ingo Weinhold 2011-06-21 00:43:30 +02:00
parent 9280379a7b
commit 3cc710798b
2 changed files with 35 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/system/kernel/fs/Vnode.h
View File

@ -28,6 +28,7 @@ struct vnode : fs_vnode, DoublyLinkedListLinkImpl<vnode> {
VMCache* cache;
struct fs_mount* mount;
struct vnode* covered_by;
struct vnode* covers;
struct advisory_locking* advisory_locking;
struct file_descriptor* mandatory_locked_by;
list_link unused_link;

66
src/system/kernel/fs/vfs.cpp
View File

@ -121,15 +121,15 @@ typedef DoublyLinkedList<vnode> VnodeList;
/*! \brief Structure to manage a mounted file system
Note: The root_vnode and covers_vnode fields (what others?) are
Note: The root_vnode and root_vnode->covers fields (what others?) are
initialized in fs_mount() and not changed afterwards. That is as soon
as the mount is mounted and it is made sure it won't be unmounted
(e.g. by holding a reference to a vnode of that mount) (read) access
to those fields is always safe, even without additional locking. Morever
while mounted the mount holds a reference to the covers_vnode, and thus
making the access path vnode->mount->covers_vnode->mount->... safe if a
reference to vnode is held (note that for the root mount covers_vnode
is NULL, though).
while mounted the mount holds a reference to the root_vnode->covers vnode,
and thus making the access path vnode->mount->root_vnode->covers->mount->...
safe if a reference to vnode is held (note that for the root mount
root_vnode->covers is NULL, though).
*/
struct fs_mount {
fs_mount()
@ -164,7 +164,6 @@ struct fs_mount {
recursive_lock rlock; // guards the vnodes list
// TODO: Make this a mutex! It is never used recursively.
struct vnode* root_vnode;
struct vnode* covers_vnode;
KPartition* partition;
VnodeList vnodes;
EntryCache entry_cache;
@ -1737,7 +1736,7 @@ replace_vnode_if_disconnected(struct fs_mount* mount,
if (vnode == mount->root_vnode) {
// redirect the vnode to the covered vnode
vnode = mount->covers_vnode;
vnode = mount->root_vnode->covers;
} else
vnode = fallBack;
@ -1933,8 +1932,8 @@ resolve_volume_root_to_mount_point(struct vnode* vnode)
struct vnode* mountPoint = NULL;
struct fs_mount* mount = vnode->mount;
if (vnode == mount->root_vnode && mount->covers_vnode) {
mountPoint = mount->covers_vnode;
if (vnode == mount->root_vnode && mount->root_vnode->covers != NULL) {
mountPoint = mount->root_vnode->covers;
inc_vnode_ref_count(mountPoint);
}
@ -2119,8 +2118,8 @@ vnode_path_to_vnode(struct vnode* vnode, char* path, bool traverseLeafLink,
path = nextPath;
continue;
} else if (vnode->mount->root_vnode == vnode
&& vnode->mount->covers_vnode) {
nextVnode = vnode->mount->covers_vnode;
&& vnode->mount->root_vnode->covers != NULL) {
nextVnode = vnode->mount->root_vnode->covers;
inc_vnode_ref_count(nextVnode);
put_vnode(vnode);
vnode = nextVnode;
@ -2427,8 +2426,8 @@ get_vnode_name(struct vnode* vnode, struct vnode* parent, struct dirent* buffer,
// vnode so we get the underlying file system
VNodePutter vnodePutter;
if (vnode->mount->root_vnode == vnode
&& vnode->mount->covers_vnode != NULL) {
vnode = vnode->mount->covers_vnode;
&& vnode->mount->root_vnode->covers != NULL) {
vnode = vnode->mount->root_vnode->covers;
inc_vnode_ref_count(vnode);
vnodePutter.SetTo(vnode);
}
@ -2938,7 +2937,7 @@ _dump_mount(struct fs_mount* mount)
kprintf(" id: %ld\n", mount->id);
kprintf(" device_name: %s\n", mount->device_name);
kprintf(" root_vnode: %p\n", mount->root_vnode);
kprintf(" covers_vnode: %p\n", mount->covers_vnode);
kprintf(" covers: %p\n", mount->root_vnode->covers);
kprintf(" partition: %p\n", mount->partition);
kprintf(" lock: %p\n", &mount->rlock);
kprintf(" flags: %s%s\n", mount->unmounting ? " unmounting" : "",
@ -2957,7 +2956,7 @@ _dump_mount(struct fs_mount* mount)
set_debug_variable("_volume", (addr_t)mount->volume->private_volume);
set_debug_variable("_root", (addr_t)mount->root_vnode);
set_debug_variable("_covers", (addr_t)mount->covers_vnode);
set_debug_variable("_covers", (addr_t)mount->root_vnode->covers);
set_debug_variable("_partition", (addr_t)mount->partition);
}
@ -3018,8 +3017,8 @@ debug_resolve_vnode_path(struct vnode* vnode, char* buffer, size_t bufferSize,
while (true) {
while (vnode->mount->root_vnode == vnode
&& vnode->mount->covers_vnode != NULL) {
vnode = vnode->mount->covers_vnode;
&& vnode->mount->root_vnode->covers != NULL) {
vnode = vnode->mount->root_vnode->covers;
}
if (vnode == sRoot) {
@ -3146,7 +3145,7 @@ dump_mounts(int argc, char** argv)
while ((mount = (struct fs_mount*)hash_next(sMountsTable, &iterator))
!= NULL) {
kprintf("%p%4ld %p %p %p %s\n", mount, mount->id, mount->root_vnode,
mount->covers_vnode, mount->volume->private_volume,
mount->root_vnode->covers, mount->volume->private_volume,
mount->volume->file_system_name);
fs_volume* volume = mount->volume;
@ -5682,7 +5681,7 @@ fix_dirent(struct vnode* parent, struct dirent* entry,
// we need to replace d_dev and d_ino with the actual values.
if (strcmp(entry->d_name, "..") == 0
&& parent->mount->root_vnode == parent
&& parent->mount->covers_vnode) {
&& parent->mount->root_vnode->covers != NULL) {
inc_vnode_ref_count(parent);
// vnode_path_to_vnode() puts the node
@ -6978,6 +6977,7 @@ fs_mount(char* path, const char* device, const char* fsName, uint32 flags,
status_t status = B_OK;
fs_volume* volume = NULL;
int32 layer = 0;
Vnode* coveredNode = NULL;
FUNCTION(("fs_mount: entry. path = '%s', fs_name = '%s'\n", path, fsName));
@ -7105,7 +7105,6 @@ fs_mount(char* path, const char* device, const char* fsName, uint32 flags,
mount->id = sNextMountID++;
mount->partition = NULL;
mount->root_vnode = NULL;
mount->covers_vnode = NULL;
mount->unmounting = false;
mount->owns_file_device = false;
mount->volume = NULL;
@ -7185,17 +7184,17 @@ fs_mount(char* path, const char* device, const char* fsName, uint32 flags,
if (status != 0)
goto err2;
} else {
status = path_to_vnode(path, true, &mount->covers_vnode, NULL, kernel);
status = path_to_vnode(path, true, &coveredNode, NULL, kernel);
if (status != B_OK)
goto err2;
// make sure covered_vnode is a directory
if (!S_ISDIR(mount->covers_vnode->Type())) {
if (!S_ISDIR(coveredNode->Type())) {
status = B_NOT_A_DIRECTORY;
goto err3;
}
if (mount->covers_vnode->mount->root_vnode == mount->covers_vnode) {
if (coveredNode->mount->root_vnode == coveredNode) {
// this is already a mount point
status = B_BUSY;
goto err3;
@ -7233,10 +7232,12 @@ fs_mount(char* path, const char* device, const char* fsName, uint32 flags,
}
// No race here, since fs_mount() is the only function changing
// covers_vnode (and holds sMountOpLock at that time).
// root_vnode->covers (and holds sMountOpLock at that time).
rw_lock_write_lock(&sVnodeLock);
if (mount->covers_vnode)
mount->covers_vnode->covered_by = mount->root_vnode;
if (coveredNode != NULL) {
mount->root_vnode->covers = coveredNode;
coveredNode->covered_by = mount->root_vnode;
}
rw_lock_write_unlock(&sVnodeLock);
if (!sRoot) {
@ -7260,16 +7261,16 @@ fs_mount(char* path, const char* device, const char* fsName, uint32 flags,
}
notify_mount(mount->id,
mount->covers_vnode ? mount->covers_vnode->device : -1,
mount->covers_vnode ? mount->covers_vnode->id : -1);
coveredNode != NULL ? coveredNode->device : -1,
coveredNode ? coveredNode->id : -1);
return mount->id;
err4:
FS_MOUNT_CALL_NO_PARAMS(mount, unmount);
err3:
if (mount->covers_vnode != NULL)
put_vnode(mount->covers_vnode);
if (coveredNode != NULL)
put_vnode(coveredNode);
err2:
mutex_lock(&sMountMutex);
hash_remove(sMountsTable, mount);
@ -7413,11 +7414,12 @@ fs_unmount(char* path, dev_t mountID, uint32 flags, bool kernel)
mount->root_vnode->ref_count--;
vnode_to_be_freed(mount->root_vnode);
mount->covers_vnode->covered_by = NULL;
Vnode* coveredNode = mount->root_vnode->covers;
coveredNode->covered_by = NULL;
vnodesWriteLocker.Unlock();
put_vnode(mount->covers_vnode);
put_vnode(coveredNode);
// Free all vnodes associated with this mount.
// They will be removed from the mount list by free_vnode(), so