From 9bc61ab18b1d41f26dc06b9e6d3c203e65f83fe6 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sun, 4 Nov 2018 03:19:03 -0500 Subject: vfs: Introduce fs_context, switch vfs_kern_mount() to it. Introduce a filesystem context concept to be used during superblock creation for mount and superblock reconfiguration for remount. This is allocated at the beginning of the mount procedure and into it is placed: (1) Filesystem type. (2) Namespaces. (3) Source/Device names (there may be multiple). (4) Superblock flags (SB_*). (5) Security details. (6) Filesystem-specific data, as set by the mount options. Accessor functions are then provided to set up a context, parameterise it from monolithic mount data (the data page passed to mount(2)) and tear it down again. A legacy wrapper is provided that implements what will be the basic operations, wrapping access to filesystems that aren't yet aware of the fs_context. Finally, vfs_kern_mount() is changed to make use of the fs_context and mount_fs() is replaced by vfs_get_tree(), called from vfs_kern_mount(). [AV -- add missing kstrdup()] [AV -- put_cred() can be unconditional - fc->cred can't be NULL] [AV -- take legacy_validate() contents into legacy_parse_monolithic()] [AV -- merge KERNEL_MOUNT and USER_MOUNT] [AV -- don't unlock superblock on success return from vfs_get_tree()] [AV -- kill 'reference' argument of init_fs_context()] Signed-off-by: David Howells Co-developed-by: Al Viro Signed-off-by: Al Viro --- fs/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/Makefile') diff --git a/fs/Makefile b/fs/Makefile index 293733f61594..5563cf34f7c2 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -12,7 +12,8 @@ obj-y := open.o read_write.o file_table.o super.o \ attr.o bad_inode.o file.o filesystems.o namespace.o \ seq_file.o xattr.o libfs.o fs-writeback.o \ pnode.o splice.o sync.o utimes.o d_path.o \ - stack.o fs_struct.o statfs.o fs_pin.o nsfs.o + stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \ + fs_context.o ifeq ($(CONFIG_BLOCK),y) obj-y += buffer.o block_dev.o direct-io.o mpage.o -- cgit From 31d921c7fb9691722ba9503b64153cdc322a7fa8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 1 Nov 2018 23:07:24 +0000 Subject: vfs: Add configuration parser helpers Because the new API passes in key,value parameters, match_token() cannot be used with it. Instead, provide three new helpers to aid with parsing: (1) fs_parse(). This takes a parameter and a simple static description of all the parameters and maps the key name to an ID. It returns 1 on a match, 0 on no match if unknowns should be ignored and some other negative error code on a parse error. The parameter description includes a list of key names to IDs, desired parameter types and a list of enumeration name -> ID mappings. [!] Note that for the moment I've required that the key->ID mapping array is expected to be sorted and unterminated. The size of the array is noted in the fsconfig_parser struct. This allows me to use bsearch(), but I'm not sure any performance gain is worth the hassle of requiring people to keep the array sorted. The parameter type array is sized according to the number of parameter IDs and is indexed directly. The optional enum mapping array is an unterminated, unsorted list and the size goes into the fsconfig_parser struct. The function can do some additional things: (a) If it's not ambiguous and no value is given, the prefix "no" on a key name is permitted to indicate that the parameter should be considered negatory. (b) If the desired type is a single simple integer, it will perform an appropriate conversion and store the result in a union in the parse result. (c) If the desired type is an enumeration, {key ID, name} will be looked up in the enumeration list and the matching value will be stored in the parse result union. (d) Optionally generate an error if the key is unrecognised. This is called something like: enum rdt_param { Opt_cdp, Opt_cdpl2, Opt_mba_mpbs, nr__rdt_params }; const struct fs_parameter_spec rdt_param_specs[nr__rdt_params] = { [Opt_cdp] = { fs_param_is_bool }, [Opt_cdpl2] = { fs_param_is_bool }, [Opt_mba_mpbs] = { fs_param_is_bool }, }; const const char *const rdt_param_keys[nr__rdt_params] = { [Opt_cdp] = "cdp", [Opt_cdpl2] = "cdpl2", [Opt_mba_mpbs] = "mba_mbps", }; const struct fs_parameter_description rdt_parser = { .name = "rdt", .nr_params = nr__rdt_params, .keys = rdt_param_keys, .specs = rdt_param_specs, .no_source = true, }; int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct fs_parse_result parse; struct rdt_fs_context *ctx = rdt_fc2context(fc); int ret; ret = fs_parse(fc, &rdt_parser, param, &parse); if (ret < 0) return ret; switch (parse.key) { case Opt_cdp: ctx->enable_cdpl3 = true; return 0; case Opt_cdpl2: ctx->enable_cdpl2 = true; return 0; case Opt_mba_mpbs: ctx->enable_mba_mbps = true; return 0; } return -EINVAL; } (2) fs_lookup_param(). This takes a { dirfd, path, LOOKUP_EMPTY? } or string value and performs an appropriate path lookup to convert it into a path object, which it will then return. If the desired type was a blockdev, the type of the looked up inode will be checked to make sure it is one. This can be used like: enum foo_param { Opt_source, nr__foo_params }; const struct fs_parameter_spec foo_param_specs[nr__foo_params] = { [Opt_source] = { fs_param_is_blockdev }, }; const char *char foo_param_keys[nr__foo_params] = { [Opt_source] = "source", }; const struct constant_table foo_param_alt_keys[] = { { "device", Opt_source }, }; const struct fs_parameter_description foo_parser = { .name = "foo", .nr_params = nr__foo_params, .nr_alt_keys = ARRAY_SIZE(foo_param_alt_keys), .keys = foo_param_keys, .alt_keys = foo_param_alt_keys, .specs = foo_param_specs, }; int foo_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct fs_parse_result parse; struct foo_fs_context *ctx = foo_fc2context(fc); int ret; ret = fs_parse(fc, &foo_parser, param, &parse); if (ret < 0) return ret; switch (parse.key) { case Opt_source: return fs_lookup_param(fc, &foo_parser, param, &parse, &ctx->source); default: return -EINVAL; } } (3) lookup_constant(). This takes a table of named constants and looks up the given name within it. The table is expected to be sorted such that bsearch() be used upon it. Possibly I should require the table be terminated and just use a for-loop to scan it instead of using bsearch() to reduce hassle. Tables look something like: static const struct constant_table bool_names[] = { { "0", false }, { "1", true }, { "false", false }, { "no", false }, { "true", true }, { "yes", true }, }; and a lookup is done with something like: b = lookup_constant(bool_names, param->string, -1); Additionally, optional validation routines for the parameter description are provided that can be enabled at compile time. A later patch will invoke these when a filesystem is registered. Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/Makefile') diff --git a/fs/Makefile b/fs/Makefile index 5563cf34f7c2..9a0b8003f069 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -13,7 +13,7 @@ obj-y := open.o read_write.o file_table.o super.o \ seq_file.o xattr.o libfs.o fs-writeback.o \ pnode.o splice.o sync.o utimes.o d_path.o \ stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \ - fs_context.o + fs_context.o fs_parser.o ifeq ($(CONFIG_BLOCK),y) obj-y += buffer.o block_dev.o direct-io.o mpage.o -- cgit