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2020-07-14fuse: reject options on reconfigure via fsconfig(2)Miklos Szeredi1-0/+1
Previous patch changed handling of remount/reconfigure to ignore all options, including those that are unknown to the fuse kernel fs. This was done for backward compatibility, but this likely only affects the old mount(2) API. The new fsconfig(2) based reconfiguration could possibly be improved. This would make the new API less of a drop in replacement for the old, OTOH this is a good chance to get rid of some weirdnesses in the old API. Several other behaviors might make sense: 1) unknown options are rejected, known options are ignored 2) unknown options are rejected, known options are rejected if the value is changed, allowed otherwise 3) all options are rejected Prior to the backward compatibility fix to ignore all options all known options were accepted (1), even if they change the value of a mount parameter; fuse_reconfigure() does not look at the config values set by fuse_parse_param(). To fix that we'd need to verify that the value provided is the same as set in the initial configuration (2). The major drawback is that this is much more complex than just rejecting all attempts at changing options (3); i.e. all options signify initial configuration values and don't make sense on reconfigure. This patch opts for (3) with the rationale that no mount options are reconfigurable in fuse. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2020-05-05docs: filesystems: convert mount_api.txt to ReSTMauro Carvalho Chehab1-1/+1
- Add a SPDX header; - Adjust document and section titles; - Some whitespace fixes and new line breaks; - Mark literal blocks as such; - Add table markups; - Add lists markups; - Add it to filesystems/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/32332c1659a28c22561cb5e64162c959856066b4.1588021877.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-07prefix-handling analogues of errorf() and friendsAl Viro1-0/+4
called errorfc/infofc/warnfc/invalfc Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-02-07add prefix to fs_context->logAl Viro1-2/+2
... turning it into struct p_log embedded into fs_context. Initialize the prefix with fs_type->name, turning fs_parse() into a trivial inline wrapper for __fs_parse(). This makes fs_parameter_description->name completely unused. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-02-07new primitive: __fs_parse()Al Viro1-4/+2
fs_parse() analogue taking p_log instead of fs_context. fs_parse() turned into a wrapper, callers in ceph_common and rbd switched to __fs_parse(). As the result, fs_parse() never gets NULL fs_context and neither do fs_context-based logging primitives Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-02-07struct p_log, variants of warnf() et.al. taking that one insteadAl Viro1-0/+11
primitives for prefixed logging Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-02-07teach logfc() to handle prefices, give it saner calling conventionsAl Viro1-6/+10
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-02-07get rid of fs_value_is_filename_emptyAl Viro1-1/+0
Its behaviour is identical to that of fs_value_is_filename. It makes no sense, anyway - LOOKUP_EMPTY affects nothing whatsoever once the pathname has been imported from userland. And both fs_value_is_filename and fs_value_is_filename_empty carry an already imported pathname. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-09-25Merge tag 'fuse-update-5.4' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse Pull fuse updates from Miklos Szeredi: - Continue separating the transport (user/kernel communication) and the filesystem layers of fuse. Getting rid of most layering violations will allow for easier cleanup and optimization later on. - Prepare for the addition of the virtio-fs filesystem. The actual filesystem will be introduced by a separate pull request. - Convert to new mount API. - Various fixes, optimizations and cleanups. * tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (55 commits) fuse: Make fuse_args_to_req static fuse: fix memleak in cuse_channel_open fuse: fix beyond-end-of-page access in fuse_parse_cache() fuse: unexport fuse_put_request fuse: kmemcg account fs data fuse: on 64-bit store time in d_fsdata directly fuse: fix missing unlock_page in fuse_writepage() fuse: reserve byteswapped init opcodes fuse: allow skipping control interface and forced unmount fuse: dissociate DESTROY from fuseblk fuse: delete dentry if timeout is zero fuse: separate fuse device allocation and installation in fuse_conn fuse: add fuse_iqueue_ops callbacks fuse: extract fuse_fill_super_common() fuse: export fuse_dequeue_forget() function fuse: export fuse_get_unique() fuse: export fuse_send_init_request() fuse: export fuse_len_args() fuse: export fuse_end_request() fuse: fix request limit ...
2019-09-06vfs: subtype handling moved to fuseDavid Howells1-1/+0
The unused vfs code can be removed. Don't pass empty subtype (same as if ->parse callback isn't called). The bits that are left involve determining whether it's permitted to split the filesystem type string passed in to mount(2). Consequently, this means that we cannot get rid of the FS_HAS_SUBTYPE flag unless we define that a type string with a dot in it always indicates a subtype specification. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2019-09-05vfs: Add a single-or-reconfig keying to vfs_get_super()David Howells1-0/+4
Add an additional keying mode to vfs_get_super() to indicate that only a single superblock should exist in the system, and that, if it does, further mounts should invoke reconfiguration upon it. This allows mount_single() to be replaced. [Fix by Eric Biggers folded in] Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-09-05vfs: Create fs_context-aware mount_bdev() replacementDavid Howells1-0/+5
Create a function, get_tree_bdev(), that is fs_context-aware and a ->get_tree() counterpart of mount_bdev(). It caches the block device pointer in the fs_context struct so that this information can be passed into sget_fc()'s test and set functions. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jens Axboe <axboe@kernel.dk> cc: linux-block@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-09-05new helper: get_tree_keyed()Al Viro1-1/+6
For vfs_get_keyed_super users. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-07-19Merge branch 'work.mount0' of ↵Linus Torvalds1-0/+7
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs mount updates from Al Viro: "The first part of mount updates. Convert filesystems to use the new mount API" * 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) mnt_init(): call shmem_init() unconditionally constify ksys_mount() string arguments don't bother with registering rootfs init_rootfs(): don't bother with init_ramfs_fs() vfs: Convert smackfs to use the new mount API vfs: Convert selinuxfs to use the new mount API vfs: Convert securityfs to use the new mount API vfs: Convert apparmorfs to use the new mount API vfs: Convert openpromfs to use the new mount API vfs: Convert xenfs to use the new mount API vfs: Convert gadgetfs to use the new mount API vfs: Convert oprofilefs to use the new mount API vfs: Convert ibmasmfs to use the new mount API vfs: Convert qib_fs/ipathfs to use the new mount API vfs: Convert efivarfs to use the new mount API vfs: Convert configfs to use the new mount API vfs: Convert binfmt_misc to use the new mount API convenience helper: get_tree_single() convenience helper get_tree_nodev() vfs: Kill sget_userns() ...
2019-07-05convenience helper: get_tree_single()Al Viro1-0/+3
counterpart of mount_single(); switch fusectl to it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-07-05convenience helper get_tree_nodev()Al Viro1-0/+3
counterpart of mount_nodev(). Switch hugetlb and pseudo to it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-06-14Merge tag 'v5.2-rc4' into mauroJonathan Corbet1-5/+1
We need to pick up post-rc1 changes to various document files so they don't get lost in Mauro's massive RST conversion push.
2019-06-08docs: fix broken documentation linksMauro Carvalho Chehab1-1/+1
Mostly due to x86 and acpi conversion, several documentation links are still pointing to the old file. Fix them. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Reviewed-by: Wolfram Sang <wsa@the-dreams.de> Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com> Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com> Acked-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-05-26vfs: Provide sb->s_iflags settings in fs_context structDavid Howells1-0/+1
Provide a field in the fs_context struct through which bits in the sb->s_iflags superblock field can be set. Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-fsdevel@vger.kernel.org
2019-05-24treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36Thomas Gleixner1-5/+1
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public licence as published by the free software foundation either version 2 of the licence or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 114 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-21vfs: Implement logging through fs_contextDavid Howells1-7/+15
Implement the ability for filesystems to log error, warning and informational messages through the fs_context. These can be extracted by userspace by reading from an fd created by fsopen(). Error messages are prefixed with "e ", warnings with "w " and informational messages with "i ". Inside the kernel, formatted messages are malloc'd but unformatted messages are not copied if they're either in the core .rodata section or in the .rodata section of the filesystem module pinned by fs_context::fs_type. The messages are only good till the fs_type is released. Note that the logging object is shared between duplicated fs_context structures. This is so that such as NFS which do a mount within a mount can get at least some of the errors from the inner mount. Five logging functions are provided for this: (1) void logfc(struct fs_context *fc, const char *fmt, ...); This logs a message into the context. If the buffer is full, the earliest message is discarded. (2) void errorf(fc, fmt, ...); This wraps logfc() to log an error. (3) void invalf(fc, fmt, ...); This wraps errorf() and returns -EINVAL for convenience. (4) void warnf(fc, fmt, ...); This wraps logfc() to log a warning. (5) void infof(fc, fmt, ...); This wraps logfc() to log an informational message. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-03-21vfs: syscall: Add fsopen() to prepare for superblock creationDavid Howells1-0/+16
Provide an fsopen() system call that starts the process of preparing to create a superblock that will then be mountable, using an fd as a context handle. fsopen() is given the name of the filesystem that will be used: int mfd = fsopen(const char *fsname, unsigned int flags); where flags can be 0 or FSOPEN_CLOEXEC. For example: sfd = fsopen("ext4", FSOPEN_CLOEXEC); fsconfig(sfd, FSCONFIG_SET_PATH, "source", "/dev/sda1", AT_FDCWD); fsconfig(sfd, FSCONFIG_SET_FLAG, "noatime", NULL, 0); fsconfig(sfd, FSCONFIG_SET_FLAG, "acl", NULL, 0); fsconfig(sfd, FSCONFIG_SET_FLAG, "user_xattr", NULL, 0); fsconfig(sfd, FSCONFIG_SET_STRING, "sb", "1", 0); fsconfig(sfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); fsinfo(sfd, NULL, ...); // query new superblock attributes mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_RELATIME); move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH); sfd = fsopen("afs", -1); fsconfig(fd, FSCONFIG_SET_STRING, "source", "#grand.central.org:root.cell", 0); fsconfig(fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); mfd = fsmount(sfd, 0, MS_NODEV); move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH); If an error is reported at any step, an error message may be available to be read() back (ENODATA will be reported if there isn't an error available) in the form: "e <subsys>:<problem>" "e SELinux:Mount on mountpoint not permitted" Once fsmount() has been called, further fsconfig() calls will incur EBUSY, even if the fsmount() fails. read() is still possible to retrieve error information. The fsopen() syscall creates a mount context and hangs it of the fd that it returns. Netlink is not used because it is optional and would make the core VFS dependent on the networking layer and also potentially add network namespace issues. Note that, for the moment, the caller must have SYS_CAP_ADMIN to use fsopen(). Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-api@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-02-28vfs: Implement logging through fs_contextDavid Howells1-4/+14
Implement the ability for filesystems to log error, warning and informational messages through the fs_context. In the future, these will be extractable by userspace by reading from an fd created by the fsopen() syscall. Error messages are prefixed with "e ", warnings with "w " and informational messages with "i ". In the future, inside the kernel, formatted messages will be malloc'd but unformatted messages will not copied if they're either in the core .rodata section or in the .rodata section of the filesystem module pinned by fs_context::fs_type. The messages will only be good till the fs_type is released. Note that the logging object will be shared between duplicated fs_context structures. This is so that such as NFS which do a mount within a mount can get at least some of the errors from the inner mount. Five logging functions are provided for this: (1) void logfc(struct fs_context *fc, const char *fmt, ...); This logs a message into the context. If the buffer is full, the earliest message is discarded. (2) void errorf(fc, fmt, ...); This wraps logfc() to log an error. (3) void invalf(fc, fmt, ...); This wraps errorf() and returns -EINVAL for convenience. (4) void warnf(fc, fmt, ...); This wraps logfc() to log a warning. (5) void infof(fc, fmt, ...); This wraps logfc() to log an informational message. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-02-28introduce cloning of fs_contextAl Viro1-0/+2
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>
2019-02-28convenience helpers: vfs_get_super() and sget_fc()Al Viro1-0/+15
the former is an analogue of mount_{single,nodev} for use in ->get_tree() instances, the latter - analogue of sget() for the same. These are fairly similar to the originals, but the callback signature for sget_fc() is different from sget() ones, so getting bits and pieces shared would be too convoluted; we might get around to that later, but for now let's just remember to keep them in sync. They do live next to each other, and changes in either won't be hard to spot. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-02-28vfs: Implement a filesystem superblock creation/configuration contextDavid Howells1-0/+5
[AV - unfuck kern_mount_data(); we want non-NULL ->mnt_ns on long-living mounts] [AV - reordering fs/namespace.c is badly overdue, but let's keep it separate from that series] [AV - drop simple_pin_fs() change] [AV - clean vfs_kern_mount() failure exits up] Implement a filesystem context concept to be used during superblock creation for mount and superblock reconfiguration for remount. The mounting procedure then becomes: (1) Allocate new fs_context context. (2) Configure the context. (3) Create superblock. (4) Query the superblock. (5) Create a mount for the superblock. (6) Destroy the context. Rather than calling fs_type->mount(), an fs_context struct is created and fs_type->init_fs_context() is called to set it up. Pointers exist for the filesystem and LSM to hang their private data off. A set of operations has to be set by ->init_fs_context() to provide freeing, duplication, option parsing, binary data parsing, validation, mounting and superblock filling. Legacy filesystems are supported by the provision of a set of legacy fs_context operations that build up a list of mount options and then invoke fs_type->mount() from within the fs_context ->get_tree() operation. This allows all filesystems to be accessed using fs_context. It should be noted that, whilst this patch adds a lot of lines of code, there is quite a bit of duplication with existing code that can be eliminated should all filesystems be converted over. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-02-28vfs: Put security flags into the fs_context structDavid Howells1-0/+1
Put security flags, such as SECURITY_LSM_NATIVE_LABELS, into the filesystem context so that the filesystem can communicate them to the LSM more easily. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-02-28vfs: Add configuration parser helpersDavid Howells1-0/+29
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>
2019-01-31vfs: Introduce logging functionsDavid Howells1-0/+42
Introduce a set of logging functions through which informational messages, warnings and error messages incurred by the mount procedure can be logged and, in a future patch, passed to userspace instead by way of the filesystem configuration context file descriptor. There are four functions: (1) infof(const char *fmt, ...); Logs an informational message. (2) warnf(const char *fmt, ...); Logs a warning message. (3) errorf(const char *fmt, ...); Logs an error message. (4) invalf(const char *fmt, ...); As errof(), but returns -EINVAL so can be used on a return statement. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-01-31introduce fs_context methodsAl Viro1-0/+13
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-01-31fs_context flavour for submountsAl Viro1-0/+3
This is an eventual replacement for vfs_submount() uses. Unlike the "mount" and "remount" cases, the users of that thing are not in VFS - they are buried in various ->d_automount() instances and rather than converting them all at once we introduce the (thankfully small and simple) infrastructure here and deal with the prospective users in afs, nfs, etc. parts of the series. Here we just introduce a new constructor (fs_context_for_submount()) along with the corresponding enum constant to be put into fc->purpose for those. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-01-31convert do_remount_sb() to fs_contextDavid Howells1-0/+4
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>
2019-01-31vfs: Introduce fs_context, switch vfs_kern_mount() to it.David Howells1-0/+64
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>