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Wong" , Kent Overstreet , Steve French , Nathan Lynch , Michael Ellerman , Thomas Zimmermann , Julien Panis , Stanislav Fomichev , Dongsheng Yang , John Groves Subject: [RFC PATCH v2 08/12] famfs: module operations & fs_context Date: Mon, 29 Apr 2024 12:04:24 -0500 Message-Id: <86694a1a663ab0b6e8e35c7b187f5ad179103482.1714409084.git.john@groves.net> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Start building up from the famfs module operations. This commit includes the following: * Register as a file system * Parse mount parameters * Allocate or find (and initialize) a superblock via famfs_get_tree() * Lookup the host dax device, and bail if it's in use (or not dax) * Register as the holder of the dax device if it's available * Add Kconfig and Makefile misc to build famfs * Add FAMFS_SUPER_MAGIC to include/uapi/linux/magic.h * Add export of fs/namei.c:may_open_dev(), which famfs needs to call * Update MAINTAINERS file for the fs/famfs/ path The following exports had to happen to enable famfs: * This uses the new fs/super.c:kill_char_super() - the other kill*super helpers were not quite right. * This uses the dev_dax_iomap export of dax_dev_get() This commit builds but is otherwise too incomplete to run Signed-off-by: John Groves --- MAINTAINERS | 1 + fs/Kconfig | 2 + fs/Makefile | 1 + fs/famfs/Kconfig | 10 ++ fs/famfs/Makefile | 5 + fs/famfs/famfs_inode.c | 345 +++++++++++++++++++++++++++++++++++++ fs/famfs/famfs_internal.h | 36 ++++ fs/namei.c | 1 + include/uapi/linux/magic.h | 1 + 9 files changed, 402 insertions(+) create mode 100644 fs/famfs/Kconfig create mode 100644 fs/famfs/Makefile create mode 100644 fs/famfs/famfs_inode.c create mode 100644 fs/famfs/famfs_internal.h diff --git a/MAINTAINERS b/MAINTAINERS index 3f2d847dcf01..365d678e2f40 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8188,6 +8188,7 @@ L: linux-cxl@vger.kernel.org L: linux-fsdevel@vger.kernel.org S: Supported F: Documentation/filesystems/famfs.rst +F: fs/famfs FANOTIFY M: Jan Kara diff --git a/fs/Kconfig b/fs/Kconfig index a46b0cbc4d8f..53b4629e92a0 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -140,6 +140,8 @@ source "fs/autofs/Kconfig" source "fs/fuse/Kconfig" source "fs/overlayfs/Kconfig" +source "fs/famfs/Kconfig" + menu "Caches" source "fs/netfs/Kconfig" diff --git a/fs/Makefile b/fs/Makefile index 6ecc9b0a53f2..3393f399a9e9 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -129,3 +129,4 @@ obj-$(CONFIG_EFIVAR_FS) += efivarfs/ obj-$(CONFIG_EROFS_FS) += erofs/ obj-$(CONFIG_VBOXSF_FS) += vboxsf/ obj-$(CONFIG_ZONEFS_FS) += zonefs/ +obj-$(CONFIG_FAMFS) += famfs/ diff --git a/fs/famfs/Kconfig b/fs/famfs/Kconfig new file mode 100644 index 000000000000..edb8980820f7 --- /dev/null +++ b/fs/famfs/Kconfig @@ -0,0 +1,10 @@ + + +config FAMFS + tristate "famfs: shared memory file system" + depends on DEV_DAX && FS_DAX && DEV_DAX_IOMAP + help + Support for the famfs file system. Famfs is a dax file system that + can support scale-out shared access to fabric-attached memory + (e.g. CXL shared memory). Famfs is not a general purpose file system; + it is an enabler for data sets in shared memory. diff --git a/fs/famfs/Makefile b/fs/famfs/Makefile new file mode 100644 index 000000000000..62230bcd6793 --- /dev/null +++ b/fs/famfs/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_FAMFS) += famfs.o + +famfs-y := famfs_inode.o diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c new file mode 100644 index 000000000000..61306240fc0b --- /dev/null +++ b/fs/famfs/famfs_inode.c @@ -0,0 +1,345 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * famfs - dax file system for shared fabric-attached memory + * + * Copyright 2023-2024 Micron Technology, inc + * + * This file system, originally based on ramfs the dax support from xfs, + * is intended to allow multiple host systems to mount a common file system + * view of dax files that map to shared memory. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "famfs_internal.h" + +#define FAMFS_DEFAULT_MODE 0755 + +static struct inode *famfs_get_inode(struct super_block *sb, + const struct inode *dir, + umode_t mode, dev_t dev) +{ + struct inode *inode = new_inode(sb); + struct timespec64 tv; + + if (!inode) + return NULL; + + inode->i_ino = get_next_ino(); + inode_init_owner(&nop_mnt_idmap, inode, dir, mode); + inode->i_mapping->a_ops = &ram_aops; + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); + mapping_set_unevictable(inode->i_mapping); + tv = inode_set_ctime_current(inode); + inode_set_mtime_to_ts(inode, tv); + inode_set_atime_to_ts(inode, tv); + + switch (mode & S_IFMT) { + default: + init_special_inode(inode, mode, dev); + break; + case S_IFREG: + inode->i_op = NULL /* famfs_file_inode_operations */; + inode->i_fop = NULL /* &famfs_file_operations */; + break; + case S_IFDIR: + inode->i_op = NULL /* famfs_dir_inode_operations */; + inode->i_fop = &simple_dir_operations; + + /* Directory inodes start off with i_nlink == 2 (for ".") */ + inc_nlink(inode); + break; + case S_IFLNK: + inode->i_op = &page_symlink_inode_operations; + inode_nohighmem(inode); + break; + } + return inode; +} + +/* + * famfs dax_operations (for char dax) + */ +static int +famfs_dax_notify_failure(struct dax_device *dax_dev, u64 offset, + u64 len, int mf_flags) +{ + struct super_block *sb = dax_holder(dax_dev); + struct famfs_fs_info *fsi = sb->s_fs_info; + + pr_err("%s: rootdev=%s offset=%lld len=%llu flags=%x\n", __func__, + fsi->rootdev, offset, len, mf_flags); + + return 0; +} + +static const struct dax_holder_operations famfs_dax_holder_ops = { + .notify_failure = famfs_dax_notify_failure, +}; + +/***************************************************************************** + * fs_context_operations + */ + +static int +famfs_fill_super(struct super_block *sb, struct fs_context *fc) +{ + int rc = 0; + + sb->s_maxbytes = MAX_LFS_FILESIZE; + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = FAMFS_SUPER_MAGIC; + sb->s_op = NULL /* famfs_super_ops */; + sb->s_time_gran = 1; + + return rc; +} + +static int +lookup_daxdev(const char *pathname, dev_t *devno) +{ + struct inode *inode; + struct path path; + int err; + + if (!pathname || !*pathname) + return -EINVAL; + + err = kern_path(pathname, LOOKUP_FOLLOW, &path); + if (err) + return err; + + inode = d_backing_inode(path.dentry); + if (!S_ISCHR(inode->i_mode)) { + err = -EINVAL; + goto out_path_put; + } + + if (!may_open_dev(&path)) { /* had to export this */ + err = -EACCES; + goto out_path_put; + } + + /* if it's dax, i_rdev is struct dax_device */ + *devno = inode->i_rdev; + +out_path_put: + path_put(&path); + return err; +} + +static int +famfs_get_tree(struct fs_context *fc) +{ + struct famfs_fs_info *fsi = fc->s_fs_info; + struct dax_device *dax_devp; + struct super_block *sb; + struct inode *inode; + dev_t daxdevno; + int err; + + /* TODO: clean up chatty messages */ + + err = lookup_daxdev(fc->source, &daxdevno); + if (err) + return err; + + fsi->daxdevno = daxdevno; + + /* This will set sb->s_dev=daxdevno */ + sb = sget_dev(fc, daxdevno); + if (IS_ERR(sb)) { + pr_err("%s: sget_dev error\n", __func__); + return PTR_ERR(sb); + } + + if (sb->s_root) { + pr_info("%s: found a matching suerblock for %s\n", + __func__, fc->source); + + /* We don't expect to find a match by dev_t; if we do, it must + * already be mounted, so we bail + */ + err = -EBUSY; + goto deactivate_out; + } else { + pr_info("%s: initializing new superblock for %s\n", + __func__, fc->source); + err = famfs_fill_super(sb, fc); + if (err) + goto deactivate_out; + } + + /* This will fail if it's not a dax device */ + dax_devp = dax_dev_get(daxdevno); + if (!dax_devp) { + pr_warn("%s: device %s not found or not dax\n", + __func__, fc->source); + err = -ENODEV; + goto deactivate_out; + } + + err = fs_dax_get(dax_devp, sb, &famfs_dax_holder_ops); + if (err) { + pr_err("%s: fs_dax_get(%lld) failed\n", __func__, (u64)daxdevno); + err = -EBUSY; + goto deactivate_out; + } + fsi->dax_devp = dax_devp; + + inode = famfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0); + sb->s_root = d_make_root(inode); + if (!sb->s_root) { + pr_err("%s: d_make_root() failed\n", __func__); + err = -ENOMEM; + fs_put_dax(fsi->dax_devp, sb); + goto deactivate_out; + } + + sb->s_flags |= SB_ACTIVE; + + WARN_ON(fc->root); + fc->root = dget(sb->s_root); + return err; + +deactivate_out: + pr_debug("%s: deactivating sb=%llx\n", __func__, (u64)sb); + deactivate_locked_super(sb); + return err; +} + +/*****************************************************************************/ + +enum famfs_param { + Opt_mode, + Opt_dax, +}; + +const struct fs_parameter_spec famfs_fs_parameters[] = { + fsparam_u32oct("mode", Opt_mode), + fsparam_string("dax", Opt_dax), + {} +}; + +static int famfs_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + struct famfs_fs_info *fsi = fc->s_fs_info; + struct fs_parse_result result; + int opt; + + opt = fs_parse(fc, famfs_fs_parameters, param, &result); + if (opt == -ENOPARAM) { + opt = vfs_parse_fs_param_source(fc, param); + if (opt != -ENOPARAM) + return opt; + + return 0; + } + if (opt < 0) + return opt; + + switch (opt) { + case Opt_mode: + fsi->mount_opts.mode = result.uint_32 & S_IALLUGO; + break; + case Opt_dax: + if (strcmp(param->string, "always")) + pr_notice("%s: invalid dax mode %s\n", + __func__, param->string); + break; + } + + return 0; +} + +static void famfs_free_fc(struct fs_context *fc) +{ + struct famfs_fs_info *fsi = fc->s_fs_info; + + if (fsi && fsi->rootdev) + kfree(fsi->rootdev); + + kfree(fsi); +} + +static const struct fs_context_operations famfs_context_ops = { + .free = famfs_free_fc, + .parse_param = famfs_parse_param, + .get_tree = famfs_get_tree, +}; + +static int famfs_init_fs_context(struct fs_context *fc) +{ + struct famfs_fs_info *fsi; + + fsi = kzalloc(sizeof(*fsi), GFP_KERNEL); + if (!fsi) + return -ENOMEM; + + fsi->mount_opts.mode = FAMFS_DEFAULT_MODE; + fc->s_fs_info = fsi; + fc->ops = &famfs_context_ops; + return 0; +} + +static void famfs_kill_sb(struct super_block *sb) +{ + struct famfs_fs_info *fsi = sb->s_fs_info; + + if (fsi->dax_devp) + fs_put_dax(fsi->dax_devp, sb); + if (fsi && fsi->rootdev) + kfree(fsi->rootdev); + kfree(fsi); + sb->s_fs_info = NULL; + + kill_char_super(sb); /* new */ +} + +#define MODULE_NAME "famfs" +static struct file_system_type famfs_fs_type = { + .name = MODULE_NAME, + .init_fs_context = famfs_init_fs_context, + .parameters = famfs_fs_parameters, + .kill_sb = famfs_kill_sb, + .fs_flags = FS_USERNS_MOUNT, +}; + +/****************************************************************************** + * Module stuff + */ +static int __init init_famfs_fs(void) +{ + int rc; + + rc = register_filesystem(&famfs_fs_type); + + return rc; +} + +static void +__exit famfs_exit(void) +{ + unregister_filesystem(&famfs_fs_type); + pr_info("%s: unregistered\n", __func__); +} + +fs_initcall(init_famfs_fs); +module_exit(famfs_exit); + +MODULE_AUTHOR("John Groves, Micron Technology"); +MODULE_LICENSE("GPL"); diff --git a/fs/famfs/famfs_internal.h b/fs/famfs/famfs_internal.h new file mode 100644 index 000000000000..951b32ec4fbd --- /dev/null +++ b/fs/famfs/famfs_internal.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * famfs - dax file system for shared fabric-attached memory + * + * Copyright 2023-2024 Micron Technology, Inc. + * + * This file system, originally based on ramfs the dax support from xfs, + * is intended to allow multiple host systems to mount a common file system + * view of dax files that map to shared memory. + */ +#ifndef FAMFS_INTERNAL_H +#define FAMFS_INTERNAL_H + +struct famfs_mount_opts { + umode_t mode; +}; + +/** + * @famfs_fs_info + * + * @mount_opts: the mount options + * @dax_devp: The underlying character devdax device + * @rootdev: Dax device path used in mount + * @daxdevno: Dax device dev_t + * @deverror: True if the dax device has called our notify_failure entry + * point, or if other "shutdown" conditions exist + */ +struct famfs_fs_info { + struct famfs_mount_opts mount_opts; + struct dax_device *dax_devp; + char *rootdev; + dev_t daxdevno; + bool deverror; +}; + +#endif /* FAMFS_INTERNAL_H */ diff --git a/fs/namei.c b/fs/namei.c index c5b2a25be7d0..f24b268473cd 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3229,6 +3229,7 @@ bool may_open_dev(const struct path *path) return !(path->mnt->mnt_flags & MNT_NODEV) && !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); } +EXPORT_SYMBOL(may_open_dev); static int may_open(struct mnt_idmap *idmap, const struct path *path, int acc_mode, int flag) diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index 1b40a968ba91..e9bdd6a415e2 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -37,6 +37,7 @@ #define HOSTFS_SUPER_MAGIC 0x00c0ffee #define OVERLAYFS_SUPER_MAGIC 0x794c7630 #define FUSE_SUPER_MAGIC 0x65735546 +#define FAMFS_SUPER_MAGIC 0x87b282ff #define MINIX_SUPER_MAGIC 0x137F /* minix v1 fs, 14 char names */ #define MINIX_SUPER_MAGIC2 0x138F /* minix v1 fs, 30 char names */