From: Paulo Alcantara <paulo@xxxxxxxx>
This patch adds support for failover when failing to connect in
cifs_mount().
Signed-off-by: Paulo Alcantara <palcantara@xxxxxxx>
Signed-off-by: Aurelien Aptel <aaptel@xxxxxxxx>
---
fs/cifs/cifs_dfs_ref.c | 20 +++--
fs/cifs/connect.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++---
fs/cifs/misc.c | 3 +
3 files changed, 224 insertions(+), 14 deletions(-)
diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 6e6953f35db2..f98e3ffa18e9 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -255,20 +255,30 @@ static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
{
struct vfsmount *mnt;
char *mountdata;
- char *devname = NULL;
+ char *devname;
+
+ /*
+ * Always pass down the DFS full path to smb3_do_mount() so we
+ * can use it later for failover.
+ */
+ devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
+ if (!devname)
+ return ERR_PTR(-ENOMEM);
+
+ convert_delimiter(devname, '/');
/* strip first '\' from fullpath */
mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
- fullpath + 1, ref, &devname);
-
- if (IS_ERR(mountdata))
+ fullpath + 1, ref, NULL);
+ if (IS_ERR(mountdata)) {
+ kfree(devname);
return (struct vfsmount *)mountdata;
+ }
mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
kfree(mountdata);
kfree(devname);
return mnt;
-
}
static void dump_referral(const struct dfs_info3_param *ref)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 92a7d028cb78..c4ce52818ed6 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3890,10 +3890,11 @@ static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
*/
static char *
build_unc_path_to_root(const struct smb_vol *vol,
- const struct cifs_sb_info *cifs_sb)
+ const struct cifs_sb_info *cifs_sb, bool useppath)
{
char *full_path, *pos;
- unsigned int pplen = vol->prepath ? strlen(vol->prepath) + 1 : 0;
+ unsigned int pplen = useppath && vol->prepath ?
+ strlen(vol->prepath) + 1 : 0;
unsigned int unc_len = strnlen(vol->UNC, MAX_TREE_SIZE + 1);
full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
@@ -3938,7 +3939,7 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
return -EREMOTE;
- full_path = build_unc_path_to_root(volume_info, cifs_sb);
+ full_path = build_unc_path_to_root(volume_info, cifs_sb, true);
if (IS_ERR(full_path))
return PTR_ERR(full_path);
@@ -3970,6 +3971,143 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
kfree(full_path);
return rc;
}
+
+static inline int get_next_dfs_tgt(const char *path,
+ struct dfs_cache_tgt_list *tgt_list,
+ struct dfs_cache_tgt_iterator **tgt_it)
+{
+ if (!*tgt_it)
+ *tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
+ else
+ *tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);
+ return !*tgt_it ? -EHOSTDOWN : 0;
+}
+
+static int update_vol_info(const struct dfs_cache_tgt_iterator *tgt_it,
+ struct smb_vol *fake_vol, struct smb_vol *vol)
+{
+ const char *tgt = dfs_cache_get_tgt_name(tgt_it);
+ int len = strlen(tgt) + 2;
+ char *new_unc;
+
+ new_unc = kmalloc(len, GFP_KERNEL);
+ if (!new_unc)
+ return -ENOMEM;
+ snprintf(new_unc, len, "\\%s", tgt);
+
+ kfree(vol->UNC);
+ vol->UNC = new_unc;
+
+ if (fake_vol->prepath) {
+ kfree(vol->prepath);
+ vol->prepath = fake_vol->prepath;
+ fake_vol->prepath = NULL;
+ }
+ memcpy(&vol->dstaddr, &fake_vol->dstaddr, sizeof(vol->dstaddr));
+
+ return 0;
+}
+
+static int setup_dfs_tgt_conn(const char *path,
+ const struct dfs_cache_tgt_iterator *tgt_it,
+ struct cifs_sb_info *cifs_sb,
+ struct smb_vol *vol,
+ unsigned int *xid,
+ struct TCP_Server_Info **server,
+ struct cifs_ses **ses,
+ struct cifs_tcon **tcon)
+{
+ int rc;
+ struct dfs_info3_param ref = {0};
+ char *mdata = NULL, *fake_devname = NULL;
+ struct smb_vol fake_vol = {0};
+
+ cifs_dbg(FYI, "%s: dfs path: %s\n", __func__, path);
+
+ rc = dfs_cache_get_tgt_referral(path, tgt_it, &ref);
+ if (rc)
+ return rc;
+
+ mdata = cifs_compose_mount_options(cifs_sb->mountdata, path, &ref,
+ &fake_devname);
+ free_dfs_info_param(&ref);
+
+ if (IS_ERR(mdata)) {
+ rc = PTR_ERR(mdata);
+ mdata = NULL;
+ } else {
+ cifs_dbg(FYI, "%s: fake_devname: %s\n", __func__, fake_devname);
+ rc = cifs_setup_volume_info(&fake_vol, mdata, fake_devname,
+ false);
+ }
+ kfree(mdata);
+ kfree(fake_devname);
+
+ if (!rc) {
+ /*
+ * We use a 'fake_vol' here because we need pass it down to the
+ * mount_{get,put} functions to test connection against new DFS
+ * targets.
+ */
+ mount_put_conns(cifs_sb, *xid, *server, *ses, *tcon);
+ rc = mount_get_conns(&fake_vol, cifs_sb, xid, server, ses,
+ tcon);
+ if (!rc) {
+ /*
+ * We were able to connect to new target server.
+ * Update current volume info with new target server.
+ */
+ rc = update_vol_info(tgt_it, &fake_vol, vol);
+ }
+ }
+ cifs_cleanup_volume_info_contents(&fake_vol);
+ return rc;
+}
+
+static int mount_do_dfs_failover(const char *path,
+ struct cifs_sb_info *cifs_sb,
+ struct smb_vol *vol,
+ struct cifs_ses *root_ses,
+ unsigned int *xid,
+ struct TCP_Server_Info **server,
+ struct cifs_ses **ses,
+ struct cifs_tcon **tcon)
+{
+ int rc;
+ struct dfs_cache_tgt_list tgt_list;
+ struct dfs_cache_tgt_iterator *tgt_it = NULL;
+
+ if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
+ return -EOPNOTSUPP;
+
+ rc = dfs_cache_noreq_find(path, NULL, &tgt_list);
+ if (rc)
+ return rc;
+
+ for (;;) {
+ /* Get next DFS target server - if any */
+ rc = get_next_dfs_tgt(path, &tgt_list, &tgt_it);
+ if (rc)
+ break;
+ /* Connect to next DFS target */
+ rc = setup_dfs_tgt_conn(path, tgt_it, cifs_sb, vol, xid, server,
+ ses, tcon);
+ if (!rc || rc == -EACCES || rc == -EOPNOTSUPP)
+ break;
+ }
+ if (!rc) {
+ /*
+ * Update DFS target hint in DFS referral cache with the target
+ * server we successfully reconnected to.
+ */
+ rc = dfs_cache_update_tgthint(*xid, root_ses ? root_ses : *ses,
+ cifs_sb->local_nls,
+ cifs_remap(cifs_sb), path,
+ tgt_it);
+ }
+ dfs_cache_free_tgts(&tgt_list);
+ return rc;
+}
#endif
static int
@@ -4122,22 +4260,36 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
int rc = 0;
unsigned int xid;
struct cifs_ses *ses;
+ struct cifs_tcon *root_tcon = NULL;
struct cifs_tcon *tcon = NULL;
struct TCP_Server_Info *server;
+ char *root_path = NULL, *full_path = NULL;
char *old_mountdata;
int count;
rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses, &tcon);
if (!rc && tcon) {
- rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
- if (!rc)
- goto out;
- if (rc != -EREMOTE)
- goto error;
+ /* If not a standalone DFS root, then check if path is remote */
+ rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
+ cifs_remap(cifs_sb), vol->UNC + 1, NULL,
+ NULL);
+ if (rc) {
+ rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
+ if (!rc)
+ goto out;
+ if (rc != -EREMOTE)
+ goto error;
+ }
}
if (rc == -EACCES || rc == -EOPNOTSUPP)
goto error;
+ root_path = build_unc_path_to_root(vol, cifs_sb, false);
+ if (IS_ERR(root_path)) {
+ rc = PTR_ERR(root_path);
+ root_path = NULL;
+ goto error;
+ }
/*
* Perform an unconditional check for whether there are DFS
@@ -4162,8 +4314,36 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
if (rc) {
if (rc == -EACCES || rc == -EOPNOTSUPP)
goto error;
+ /* Perform DFS failover to any other DFS targets */
+ rc = mount_do_dfs_failover(root_path + 1, cifs_sb, vol, NULL,
+ &xid, &server, &ses, &tcon);
+ if (rc)
+ goto error;
}
+ kfree(root_path);
+ root_path = build_unc_path_to_root(vol, cifs_sb, false);
+ if (IS_ERR(root_path)) {
+ rc = PTR_ERR(root_path);
+ root_path = NULL;
+ goto error;
+ }
+ /* Cache out resolved root server */
+ (void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
+ root_path + 1, NULL, NULL);
+ /*
+ * Save root tcon for additional DFS requests to update or create a new
+ * DFS cache entry, or even perform DFS failover.
+ */
+ spin_lock(&cifs_tcp_ses_lock);
+ tcon->tc_count++;
+ tcon->dfs_path = root_path;
+ root_path = NULL;
+ tcon->remap = cifs_remap(cifs_sb);
+ spin_unlock(&cifs_tcp_ses_lock);
+
+ root_tcon = tcon;
+
for (count = 1; ;) {
if (!rc && tcon) {
rc = is_path_remote(cifs_sb, vol, xid, server, tcon);
@@ -4181,8 +4361,16 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
break;
}
+ kfree(full_path);
+ full_path = build_unc_path_to_root(vol, cifs_sb, true);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
+ full_path = NULL;
+ break;
+ }
+
old_mountdata = cifs_sb->mountdata;
- rc = expand_dfs_referral(xid, tcon->ses, vol, cifs_sb,
+ rc = expand_dfs_referral(xid, root_tcon->ses, vol, cifs_sb,
true);
if (rc)
break;
@@ -4193,11 +4381,18 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
&tcon);
}
if (rc) {
+ if (rc == -EACCES || rc == -EOPNOTSUPP)
+ break;
+ /* Perform DFS failover to any other DFS targets */
+ rc = mount_do_dfs_failover(full_path + 1, cifs_sb, vol,
+ root_tcon->ses, &xid,
+ &server, &ses, &tcon);
if (rc == -EACCES || rc == -EOPNOTSUPP || !server ||
!ses)
goto error;
}
}
+ cifs_put_tcon(root_tcon);
if (rc)
goto error;
@@ -4213,6 +4408,8 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
return mount_setup_tlink(cifs_sb, ses, tcon);
error:
+ kfree(full_path);
+ kfree(root_path);
mount_put_conns(cifs_sb, xid, server, ses, tcon);
return rc;
}
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 5e315e4009e2..1e1bf1759247 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -140,6 +140,9 @@ tconInfoFree(struct cifs_tcon *buf_to_free)
kfree(buf_to_free->nativeFileSystem);
kzfree(buf_to_free->password);
kfree(buf_to_free->crfid.fid);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ kfree(buf_to_free->dfs_path);
+#endif
kfree(buf_to_free);
}
--
2.13.7
