fs/smb/client/fscache.c

Source file repositories/reference/linux-study-clean/fs/smb/client/fscache.c

File Facts

System
Linux kernel
Corpus path
fs/smb/client/fscache.c
Extension
.c
Size
4604 bytes
Lines
173
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct cifs_fscache_inode_key {

	__le64  uniqueid;	/* server inode number */
	__le64  createtime;	/* creation time on server */
	u8	type;		/* S_IFMT file type */
} __packed;

static void cifs_fscache_fill_volume_coherency(
	struct cifs_tcon *tcon,
	struct cifs_fscache_volume_coherency_data *cd)
{
	memset(cd, 0, sizeof(*cd));
	cd->resource_id		= cpu_to_le64(tcon->resource_id);
	cd->vol_create_time	= tcon->vol_create_time;
	cd->vol_serial_number	= cpu_to_le32(tcon->vol_serial_number);
}

int cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
{
	struct cifs_fscache_volume_coherency_data cd;
	struct TCP_Server_Info *server = tcon->ses->server;
	struct fscache_volume *vcookie;
	const struct sockaddr *sa = (struct sockaddr *)&server->dstaddr;
	size_t slen, i;
	char *sharename;
	char *key;
	int ret = -ENOMEM;

	if (tcon->fscache_acquired)
		return 0;

	mutex_lock(&tcon->fscache_lock);
	if (tcon->fscache_acquired) {
		mutex_unlock(&tcon->fscache_lock);
		return 0;
	}
	tcon->fscache_acquired = true;

	tcon->fscache = NULL;
	switch (sa->sa_family) {
	case AF_INET:
	case AF_INET6:
		break;
	default:
		mutex_unlock(&tcon->fscache_lock);
		cifs_dbg(VFS, "Unknown network family '%d'\n", sa->sa_family);
		return -EINVAL;
	}

	memset(&key, 0, sizeof(key));

	sharename = extract_sharename(tcon->tree_name);
	if (IS_ERR(sharename)) {
		mutex_unlock(&tcon->fscache_lock);
		cifs_dbg(FYI, "%s: couldn't extract sharename\n", __func__);
		return PTR_ERR(sharename);
	}

	slen = strlen(sharename);
	for (i = 0; i < slen; i++)
		if (sharename[i] == '/')
			sharename[i] = ';';

	key = kasprintf(GFP_KERNEL, "cifs,%pISpc,%s", sa, sharename);
	if (!key)
		goto out;

	cifs_fscache_fill_volume_coherency(tcon, &cd);
	vcookie = fscache_acquire_volume(key,
					 NULL, /* preferred_cache */
					 &cd, sizeof(cd));
	cifs_dbg(FYI, "%s: (%s/0x%p)\n", __func__, key, vcookie);
	if (IS_ERR(vcookie)) {
		if (vcookie != ERR_PTR(-EBUSY)) {
			ret = PTR_ERR(vcookie);
			goto out_2;
		}
		pr_err("Cache volume key already in use (%s)\n", key);
		vcookie = NULL;
		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
				    netfs_trace_tcon_ref_see_fscache_collision);
	} else {
		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
				    netfs_trace_tcon_ref_see_fscache_okay);
	}

	tcon->fscache = vcookie;
	ret = 0;
out_2:
	kfree(key);

Annotation

Implementation Notes