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 <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replace do_remount_sb() with a function, reconfigure_super(), that's fs_context aware. The fs_context is expected to be parameterised already and have ->root pointing to the superblock to be reconfigured. A legacy wrapper is provided that is intended to be called from the fs_context ops when those appear, but for now is called directly from reconfigure_super(). This wrapper invokes the ->remount_fs() superblock op for the moment. It is intended that the remount_fs() op will be phased out. The fs_context->purpose is set to FS_CONTEXT_FOR_RECONFIGURE to indicate that the context is being used for reconfiguration. do_umount_root() is provided to consolidate remount-to-R/O for umount and emergency remount by creating a context and invoking reconfiguration. do_remount(), do_umount() and do_emergency_remount_callback() are switched to use the new process. [AV -- fold UMOUNT and EMERGENCY_REMOUNT in; fixes the umount / bug, gets rid of pointless complexity] [AV -- set ->net_ns in all cases; nfs remount will need that] [AV -- shift security_sb_remount() call into reconfigure_super(); the callers that didn't do security_sb_remount() have NULL fc->security anyway, so it's a no-op for them] Signed-off-by: David Howells <dhowells@redhat.com> Co-developed-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Right now vfs_get_tree() calls security_sb_kern_mount() (i.e.
mount MAC) unless it gets MS_KERNMOUNT or MS_SUBMOUNT in flags.
Doing it that way is both clumsy and imprecise.
Consider the callers' tree of vfs_get_tree():
vfs_get_tree()
<- do_new_mount()
<- vfs_kern_mount()
<- simple_pin_fs()
<- vfs_submount()
<- kern_mount_data()
<- init_mount_tree()
<- btrfs_mount()
<- vfs_get_tree()
<- nfs_do_root_mount()
<- nfs4_try_mount()
<- nfs_fs_mount()
<- vfs_get_tree()
<- nfs4_referral_mount()
do_new_mount() always does need MAC (we are guaranteed that neither
MS_KERNMOUNT nor MS_SUBMOUNT will be passed there).
simple_pin_fs(), vfs_submount() and kern_mount_data() pass explicit
flags inhibiting that check. So does nfs4_referral_mount() (the
flags there are ulimately coming from vfs_submount()).
init_mount_tree() is called too early for anything LSM-related; it
doesn't matter whether we attempt those checks, they'll do nothing.
Finally, in case of btrfs_mount() and nfs_fs_mount(), doing MAC
is pointless - either the caller will do it, or the flags are
such that we wouldn't have done it either.
In other words, the one and only case when we want that check
done is when we are called from do_new_mount(), and there we
want it unconditionally.
So let's simply move it there. The superblock is still locked,
so nobody is going to get access to it (via ustat(2), etc.)
until we get a chance to apply the checks - we are free to
move them to any point up to where we drop ->s_umount (in
do_new_mount_fc()).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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 <dhowells@redhat.com> Co-developed-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull overlayfs updates from Miklos Szeredi:
"This contains two new features:
- Stack file operations: this allows removal of several hacks from
the VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
- Metadata only copy-up: when file is on lower layer and only
metadata is modified (except size) then only copy up the metadata
and continue to use the data from the lower file"
* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
ovl: Enable metadata only feature
ovl: Do not do metacopy only for ioctl modifying file attr
ovl: Do not do metadata only copy-up for truncate operation
ovl: add helper to force data copy-up
ovl: Check redirect on index as well
ovl: Set redirect on upper inode when it is linked
ovl: Set redirect on metacopy files upon rename
ovl: Do not set dentry type ORIGIN for broken hardlinks
ovl: Add an inode flag OVL_CONST_INO
ovl: Treat metacopy dentries as type OVL_PATH_MERGE
ovl: Check redirects for metacopy files
ovl: Move some dir related ovl_lookup_single() code in else block
ovl: Do not expose metacopy only dentry from d_real()
ovl: Open file with data except for the case of fsync
ovl: Add helper ovl_inode_realdata()
ovl: Store lower data inode in ovl_inode
ovl: Fix ovl_getattr() to get number of blocks from lower
ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
ovl: Copy up meta inode data from lowest data inode
ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
...
Pull fs iomap refactoring from Darrick Wong: "This is the first part of the XFS changes for 4.19. Christoph and Andreas coordinated some refactoring work on the iomap code in preparation for removing buffer heads from XFS and porting gfs2 to iomap. I'm sending this small pull request ahead of the main XFS merge to avoid holding up gfs2 unnecessarily" * 'iomap-4.19-merge' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: iomap: add inline data support to iomap_readpage_actor iomap: support direct I/O to inline data iomap: refactor iomap_dio_actor iomap: add initial support for writes without buffer heads iomap: add an iomap-based readpage and readpages implementation iomap: add private pointer to struct iomap iomap: add a page_done callback iomap: generic inline data handling iomap: complete partial direct I/O writes synchronously iomap: mark newly allocated buffer heads as new fs: factor out a __generic_write_end helper
This reverts commit 598e3c8f72f5b77c84d2cb26cfd936ffb3cfdbaa. Overlayfs no longer relies on the vfs correct atime handling. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This reverts commit 7c6893e3c9abf6a9676e060a1e35e5caca673d57. Overlayfs no longer relies on the vfs for checking writability of files. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is needed by the stacked ioctl implementation in overlayfs. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>