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smb:client: smb: client: Add reverse mapping from tcon to superblocks

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Currently, when a SMB connection is reset and renegotiated with the
server, there's no way to update all related mount points with new
negotiated sizes. This is because while superblocks (cifs_sb_info)
maintain references to tree connections (tcon) through tcon_link
structures, there is no reverse mapping from a tcon back to all the
superblocks using it.

This patch adds a bidirectional relationship between tcon and
cifs_sb_info structures by:

1. Adding a cifs_sb_list to tcon structure with appropriate locking
2. Adding tcon_sb_link to cifs_sb_info to join the list
3. Managing the list entries during mount and umount operations

The bidirectional relationship enables future functionality to locate and
update all superblocks connected to a specific tree connection, such as:

- Updating negotiated parameters after reconnection
- Efficiently notifying all affected mounts of capability changes

This is the first part of a series to improve connection resilience
by keeping all mount parameters in sync with server capabilities
after reconnection.

Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Wang Zhaolong 2025-03-31 21:33:13 +08:00 committed by Steve French
parent be5d361e30
commit a091d9711b
4 changed files with 20 additions and 1 deletions
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1
fs/smb/client/cifs_fs_sb.h
View File

@ -49,6 +49,7 @@
struct cifs_sb_info {
struct rb_root tlink_tree;
struct list_head tcon_sb_link;
spinlock_t tlink_tree_lock;
struct tcon_link *master_tlink;
struct nls_table *local_nls;

3
fs/smb/client/cifsglob.h
View File

@ -1321,7 +1321,8 @@ struct cifs_tcon {
#endif
struct list_head pending_opens; /* list of incomplete opens */
struct cached_fids *cfids;
/* BB add field for back pointer to sb struct(s)? */
struct list_head cifs_sb_list;
spinlock_t sb_list_lock;
#ifdef CONFIG_CIFS_DFS_UPCALL
struct delayed_work dfs_cache_work;
struct list_head dfs_ses_list;

15
fs/smb/client/connect.c
View File

@ -3477,6 +3477,7 @@ int cifs_setup_cifs_sb(struct cifs_sb_info *cifs_sb)
struct smb3_fs_context *ctx = cifs_sb->ctx;
INIT_DELAYED_WORK(&cifs_sb->prune_tlinks, cifs_prune_tlinks);
INIT_LIST_HEAD(&cifs_sb->tcon_sb_link);
spin_lock_init(&cifs_sb->tlink_tree_lock);
cifs_sb->tlink_tree = RB_ROOT;
@ -3709,6 +3710,10 @@ static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
spin_unlock(&cifs_sb->tlink_tree_lock);
spin_lock(&tcon->sb_list_lock);
list_add(&cifs_sb->tcon_sb_link, &tcon->cifs_sb_list);
spin_unlock(&tcon->sb_list_lock);
queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
TLINK_IDLE_EXPIRE);
return 0;
@ -4050,9 +4055,19 @@ cifs_umount(struct cifs_sb_info *cifs_sb)
struct rb_root *root = &cifs_sb->tlink_tree;
struct rb_node *node;
struct tcon_link *tlink;
struct cifs_tcon *tcon = NULL;
cancel_delayed_work_sync(&cifs_sb->prune_tlinks);
if (cifs_sb->master_tlink) {
tcon = cifs_sb->master_tlink->tl_tcon;
if (tcon) {
spin_lock(&tcon->sb_list_lock);
list_del_init(&cifs_sb->tcon_sb_link);
spin_unlock(&tcon->sb_list_lock);
}
}
spin_lock(&cifs_sb->tlink_tree_lock);
while ((node = rb_first(root))) {
tlink = rb_entry(node, struct tcon_link, tl_rbnode);

2
fs/smb/client/misc.c
View File

@ -137,8 +137,10 @@ tcon_info_alloc(bool dir_leases_enabled, enum smb3_tcon_ref_trace trace)
spin_lock_init(&ret_buf->tc_lock);
INIT_LIST_HEAD(&ret_buf->openFileList);
INIT_LIST_HEAD(&ret_buf->tcon_list);
INIT_LIST_HEAD(&ret_buf->cifs_sb_list);
spin_lock_init(&ret_buf->open_file_lock);
spin_lock_init(&ret_buf->stat_lock);
spin_lock_init(&ret_buf->sb_list_lock);
atomic_set(&ret_buf->num_local_opens, 0);
atomic_set(&ret_buf->num_remote_opens, 0);
ret_buf->stats_from_time = ktime_get_real_seconds();