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authorAl Viro <viro@zeniv.linux.org.uk>2018-12-23 22:02:47 +0100
committerAl Viro <viro@zeniv.linux.org.uk>2019-02-28 09:29:27 +0100
commit0b52075ee62301dd150c9f2c3ddd0035ed894cde (patch)
treebb5b54d2fee0e0e37f73635030dc0e25e93c9aa5 /fs/fs_context.c
parentconvenience helpers: vfs_get_super() and sget_fc() (diff)
downloadlinux-0b52075ee62301dd150c9f2c3ddd0035ed894cde.tar.xz
linux-0b52075ee62301dd150c9f2c3ddd0035ed894cde.zip
introduce cloning of fs_context
new primitive: vfs_dup_fs_context(). Comes with fs_context method (->dup()) for copying the filesystem-specific parts of fs_context, along with LSM one (->fs_context_dup()) for doing the same to LSM parts. [needs better commit message, and change of Author:, anyway] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/fs_context.c')
-rw-r--r--fs/fs_context.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/fs/fs_context.c b/fs/fs_context.c
index aa7e0ffb591a..57f61833ac83 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -338,6 +338,47 @@ void fc_drop_locked(struct fs_context *fc)
static void legacy_fs_context_free(struct fs_context *fc);
/**
+ * vfs_dup_fc_config: Duplicate a filesystem context.
+ * @src_fc: The context to copy.
+ */
+struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
+{
+ struct fs_context *fc;
+ int ret;
+
+ if (!src_fc->ops->dup)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
+ if (!fc)
+ return ERR_PTR(-ENOMEM);
+
+ fc->fs_private = NULL;
+ fc->s_fs_info = NULL;
+ fc->source = NULL;
+ fc->security = NULL;
+ get_filesystem(fc->fs_type);
+ get_net(fc->net_ns);
+ get_user_ns(fc->user_ns);
+ get_cred(fc->cred);
+
+ /* Can't call put until we've called ->dup */
+ ret = fc->ops->dup(fc, src_fc);
+ if (ret < 0)
+ goto err_fc;
+
+ ret = security_fs_context_dup(fc, src_fc);
+ if (ret < 0)
+ goto err_fc;
+ return fc;
+
+err_fc:
+ put_fs_context(fc);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(vfs_dup_fs_context);
+
+/**
* put_fs_context - Dispose of a superblock configuration context.
* @fc: The context to dispose of.
*/
@@ -381,6 +422,31 @@ static void legacy_fs_context_free(struct fs_context *fc)
}
/*
+ * Duplicate a legacy config.
+ */
+static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
+{
+ struct legacy_fs_context *ctx;
+ struct legacy_fs_context *src_ctx = src_fc->fs_private;
+
+ ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) {
+ ctx->legacy_data = kmemdup(src_ctx->legacy_data,
+ src_ctx->data_size, GFP_KERNEL);
+ if (!ctx->legacy_data) {
+ kfree(ctx);
+ return -ENOMEM;
+ }
+ }
+
+ fc->fs_private = ctx;
+ return 0;
+}
+
+/*
* Add a parameter to a legacy config. We build up a comma-separated list of
* options.
*/
@@ -514,6 +580,7 @@ static int legacy_reconfigure(struct fs_context *fc)
const struct fs_context_operations legacy_fs_context_ops = {
.free = legacy_fs_context_free,
+ .dup = legacy_fs_context_dup,
.parse_param = legacy_parse_param,
.parse_monolithic = legacy_parse_monolithic,
.get_tree = legacy_get_tree,