| Message ID | 1385000024-23463-2-git-send-email-mark.doffman@codethink.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
[adding linux-fsdevel] Hi Mark! There was a question on this thread earlier about whether it makes sense to support this in-kernel or make users build an initrd. This looks pretty simple to me and is certainly easier for users, so (with some adjustments) I'm happy with it, but I think the folks on linux-fsdevel may have a more informed opinion than do. See below for a few comments... On Wed, 20 Nov 2013, mark.doffman@codethink.co.uk wrote: > From: Mark Doffman <mark.doffman@codethink.co.uk> > > Analogous to NFS add a new root device option, the ability > to boot using the Ceph networked file system as the root fs. > > This patch adds a new root device option '/dev/ceph' that > uses a ceph networked file system. File system parameters > are passed using a new kernel parameter: 'cephroot'. > > The 'cephroot' parameters are very similar to 'nfsroot'. > > Signed-off-by: Mark Doffman <mark.doffman@codethink.co.uk> > Reviewed-by: Ian Molton <ian.molton@codethink.co.uk> > --- > fs/ceph/Kconfig | 10 +++ > fs/ceph/Makefile | 1 + > fs/ceph/root.c | 163 +++++++++++++++++++++++++++++++++++++++++ > include/linux/ceph/ceph_root.h | 10 +++ > include/linux/root_dev.h | 1 + > init/do_mounts.c | 32 +++++++- > 6 files changed, 216 insertions(+), 1 deletion(-) > create mode 100644 fs/ceph/root.c > create mode 100644 include/linux/ceph/ceph_root.h > > diff --git a/fs/ceph/Kconfig b/fs/ceph/Kconfig > index ac9a2ef..325e83d 100644 > --- a/fs/ceph/Kconfig > +++ b/fs/ceph/Kconfig > @@ -25,3 +25,13 @@ config CEPH_FSCACHE > caching support for Ceph clients using FS-Cache > > endif > + > +config ROOT_CEPH > + bool "Root file system on Ceph FS" > + depends on CEPH_FS=y && IP_PNP > + help > + If you want your system to mount its root file system via CEPH, > + choose Y here. For details, read > + <file:Documentation/filesystems/ceph/cephroot.txt>. > + > + If unsure say N. > diff --git a/fs/ceph/Makefile b/fs/ceph/Makefile > index 32e3010..af2dcbf 100644 > --- a/fs/ceph/Makefile > +++ b/fs/ceph/Makefile > @@ -10,3 +10,4 @@ ceph-y := super.o inode.o dir.o file.o locks.o addr.o ioctl.o \ > debugfs.o > > ceph-$(CONFIG_CEPH_FSCACHE) += cache.o > +ceph-$(CONFIG_ROOT_CEPH) += root.o > diff --git a/fs/ceph/root.c b/fs/ceph/root.c > new file mode 100644 > index 0000000..bff67fb > --- /dev/null > +++ b/fs/ceph/root.c > @@ -0,0 +1,163 @@ > +/* > + * Copyright (C) 2012 Codethink Ltd. <mark.doffman@codethink.co.uk> > + * > + * This file is released under the GPL v2 > + * > + * Allow a CephFS filesystem to be mounted as root. > + */ > + > +#include <linux/kernel.h> > +#include <linux/types.h> > +#include <linux/string.h> > +#include <linux/init.h> > +#include <linux/slab.h> > +#include <linux/utsname.h> > +#include <linux/root_dev.h> > +#include <linux/in.h> > +#include <net/ipconfig.h> > +#include <linux/ceph/ceph_root.h> > + > +/* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */ > +extern __be32 root_nfs_parse_addr(char *name); /*__init*/ > + > +#define MAXPATHLEN 1024 > + > +/* Parameters passed from the kernel command line */ > +static char ceph_root_params[256] __initdata; > + > +/* Address of CEPH server */ > +static __be32 servaddr __initdata = htonl(INADDR_NONE); IPv4 only? > + > +/* Name of directory to mount */ > +static char ceph_export_path[MAXPATHLEN + 1] __initdata; > + > +/* Text-based mount options */ > +static char ceph_root_options[256] __initdata; > + > +/* server:path string passed to mount */ > +static char ceph_root_device[MAXPATHLEN + 1] __initdata; > + > +/* Address of CEPH server */ > +static __be32 root_ceph_server_addr = htonl(INADDR_NONE); > + > +/* > + * Parse out root export path and mount options from > + * passed-in string @incoming. > + * > + * Copy the export path into @exppath. > + * > + * Returns 0 on success -E2BIG if the resulting options string is too long. > + */ > +static int __init root_ceph_parse_options(char *incoming, char *exppath, > + const size_t exppathlen) > +{ > + char *p; > + int res = 0; > + > + /* > + * Set the remote path > + */ > + p = strsep(&incoming, ","); > + if (*p != '\0' && strcmp(p, "default") != 0) > + strlcpy(exppath, p, exppathlen); > + > + /* > + * @incoming now points to the rest of the string; if it > + * contains something, append it to our root options buffer > + */ > + if (incoming != NULL && *incoming != '\0') { > + size_t len = strlen(ceph_root_options); > + size_t destlen = sizeof(ceph_root_options); > + > + if (len && ceph_root_options[len - 1] != ',') { > + if (strlcat(ceph_root_options, ",", destlen) > destlen) > + res = -E2BIG; > + } > + > + if (strlcat(ceph_root_options, incoming, destlen) > destlen) > + res = -E2BIG; > + > + } > + return res; > +} > + > +/* > + * Parse CephFS server and directory information passed on the kernel > + * command line. > + * > + * cephroot=[<server-ip>:]<root-dir>[,<cephfs-options>] > + */ I think we would be better off using the parsing code in fs/ceph/super.c, which handles both IPv4 and IPv6, and more importantly lets you provide a list of monitors. Providing only a single server IP makes it a single point of failure during mount (though of course if/when we connect we will discover the current set of mons). Attaching the options at the end doesn't appeal to me cosmetically, but I can see how it's useful to have it all in a single string that DHCP can provide. sage > +static int __init ceph_root_setup(char *line) > +{ > + ROOT_DEV = Root_CEPH; > + > + strlcpy(ceph_root_params, line, sizeof(ceph_root_params)); > + > + /* > + * Note: root_nfs_parse_addr() removes the server-ip from > + * ceph_root_params, if it exists. > + */ > + root_ceph_server_addr = root_nfs_parse_addr(ceph_root_params); > + > + return 1; > +} > + > +__setup("cephroot=", ceph_root_setup); > + > +/* > + * ceph_root_data - Return mount device and data for CEPHROOT mount. > + * > + * @root_device: OUT: Address of string containing CEPHROOT device. > + * @root_data: OUT: Address of string containing CEPHROOT mount options. > + * > + * Returns: 0 and sets @root_device and @root_data if successful. > + * error code if unsuccessful. > + */ > +int __init ceph_root_data(char **root_device, char **root_data) > +{ > + char *tmp = NULL; > + const size_t tmplen = sizeof(ceph_export_path); > + int len; > + int ret = -E2BIG; > + > + servaddr = root_ceph_server_addr; > + if (servaddr == htonl(INADDR_NONE)) > + return -ENOENT; > + > + tmp = kzalloc(tmplen, GFP_KERNEL); > + if (tmp == NULL) > + return -ENOMEM; > + > + if (ceph_root_params[0] != '\0') { > + if (root_ceph_parse_options(ceph_root_params, tmp, tmplen)) > + goto out; > + } > + > + /* > + * Set up ceph_root_device. This looks like: server:/path > + * > + * At this point, utsname()->nodename contains our local > + * IP address or hostname, set by ipconfig. If "%s" exists > + * in tmp, substitute the nodename, then shovel the whole > + * mess into ceph_root_device. > + */ > + len = snprintf(ceph_export_path, sizeof(ceph_export_path), > + tmp, utsname()->nodename); > + if (len > (int)sizeof(ceph_export_path)) > + goto out; > + len = snprintf(ceph_root_device, sizeof(ceph_root_device), > + "%pI4:%s", &servaddr, ceph_export_path); > + if (len > (int)sizeof(ceph_root_device)) > + goto out; > + > + pr_debug("Root-CEPH: Root device: %s\n", ceph_root_device); > + pr_debug("Root-CEPH: Root options: %s\n", ceph_root_options); > + *root_device = ceph_root_device; > + *root_data = ceph_root_options; > + > + ret = 0; > + > +out: > + kfree(tmp); > + return ret; > +} > diff --git a/include/linux/ceph/ceph_root.h b/include/linux/ceph/ceph_root.h > new file mode 100644 > index 0000000..e6bae63 > --- /dev/null > +++ b/include/linux/ceph/ceph_root.h > @@ -0,0 +1,10 @@ > +/* > + * Copyright (C) 2012 Codethink Ltd. <mark.doffman@codethink.co.uk> > + * > + * This file is released under the GPL v2 > + * > + * ceph_root.h > + */ > + > +/* linux/fs/ceph/root.c */ > +extern int ceph_root_data(char **root_device, char **root_data); /*__init*/ > diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h > index ed241aa..af6b182 100644 > --- a/include/linux/root_dev.h > +++ b/include/linux/root_dev.h > @@ -16,6 +16,7 @@ enum { > Root_SDA2 = MKDEV(SCSI_DISK0_MAJOR, 2), > Root_HDC1 = MKDEV(IDE1_MAJOR, 1), > Root_SR0 = MKDEV(SCSI_CDROM_MAJOR, 0), > + Root_CEPH = MKDEV(UNNAMED_MAJOR, 254), > }; > > extern dev_t ROOT_DEV; > diff --git a/init/do_mounts.c b/init/do_mounts.c > index 8e5addc..d075020 100644 > --- a/init/do_mounts.c > +++ b/init/do_mounts.c > @@ -33,6 +33,8 @@ > #include <linux/nfs_fs_sb.h> > #include <linux/nfs_mount.h> > > +#include <linux/ceph/ceph_root.h> > + > #include "do_mounts.h" > > int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */ > @@ -199,6 +201,7 @@ done: > * a partition with a known unique id. > * 8) <major>:<minor> major and minor number of the device separated by > * a colon. > + * 9) /dev/ceph represents Root_CEPH > * > * If name doesn't have fall into the categories above, we return (0,0). > * block_class is used to check if something is a disk name. If the disk > @@ -245,7 +248,9 @@ dev_t name_to_dev_t(char *name) > res = Root_RAM0; > if (strcmp(name, "ram") == 0) > goto done; > - > + res = Root_CEPH; > + if (strcmp(name, "ceph") == 0) > + goto done; > if (strlen(name) > 31) > goto fail; > strcpy(s, name); > @@ -473,6 +478,22 @@ static int __init mount_nfs_root(void) > } > #endif > > +#ifdef CONFIG_ROOT_CEPH > +static int __init mount_ceph_root(void) > +{ > + char *root_dev, *root_data; > + > + if (ceph_root_data(&root_dev, &root_data)) > + return 0; > + > + if (do_mount_root(root_dev, "ceph", > + root_mountflags, root_data)) > + return 0; > + > + return 1; > +} > +#endif > + > #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD) > void __init change_floppy(char *fmt, ...) > { > @@ -514,6 +535,15 @@ void __init mount_root(void) > ROOT_DEV = Root_FD0; > } > #endif > +#ifdef CONFIG_ROOT_CEPH > + if (ROOT_DEV == Root_CEPH) { > + if (mount_ceph_root()) > + return; > + > + printk(KERN_ERR "VFS: Unable to mount root fs via CephFS, trying floppy.\n"); > + ROOT_DEV = Root_FD0; > + } > +#endif > #ifdef CONFIG_BLK_DEV_FD > if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) { > /* rd_doload is 2 for a dual initrd/ramload setup */ > -- > 1.8.4 > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ceph/Kconfig b/fs/ceph/Kconfig index ac9a2ef..325e83d 100644 --- a/fs/ceph/Kconfig +++ b/fs/ceph/Kconfig @@ -25,3 +25,13 @@ config CEPH_FSCACHE caching support for Ceph clients using FS-Cache endif + +config ROOT_CEPH + bool "Root file system on Ceph FS" + depends on CEPH_FS=y && IP_PNP + help + If you want your system to mount its root file system via CEPH, + choose Y here. For details, read + <file:Documentation/filesystems/ceph/cephroot.txt>. + + If unsure say N. diff --git a/fs/ceph/Makefile b/fs/ceph/Makefile index 32e3010..af2dcbf 100644 --- a/fs/ceph/Makefile +++ b/fs/ceph/Makefile @@ -10,3 +10,4 @@ ceph-y := super.o inode.o dir.o file.o locks.o addr.o ioctl.o \ debugfs.o ceph-$(CONFIG_CEPH_FSCACHE) += cache.o +ceph-$(CONFIG_ROOT_CEPH) += root.o diff --git a/fs/ceph/root.c b/fs/ceph/root.c new file mode 100644 index 0000000..bff67fb --- /dev/null +++ b/fs/ceph/root.c @@ -0,0 +1,163 @@ +/* + * Copyright (C) 2012 Codethink Ltd. <mark.doffman@codethink.co.uk> + * + * This file is released under the GPL v2 + * + * Allow a CephFS filesystem to be mounted as root. + */ + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/string.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/utsname.h> +#include <linux/root_dev.h> +#include <linux/in.h> +#include <net/ipconfig.h> +#include <linux/ceph/ceph_root.h> + +/* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */ +extern __be32 root_nfs_parse_addr(char *name); /*__init*/ + +#define MAXPATHLEN 1024 + +/* Parameters passed from the kernel command line */ +static char ceph_root_params[256] __initdata; + +/* Address of CEPH server */ +static __be32 servaddr __initdata = htonl(INADDR_NONE); + +/* Name of directory to mount */ +static char ceph_export_path[MAXPATHLEN + 1] __initdata; + +/* Text-based mount options */ +static char ceph_root_options[256] __initdata; + +/* server:path string passed to mount */ +static char ceph_root_device[MAXPATHLEN + 1] __initdata; + +/* Address of CEPH server */ +static __be32 root_ceph_server_addr = htonl(INADDR_NONE); + +/* + * Parse out root export path and mount options from + * passed-in string @incoming. + * + * Copy the export path into @exppath. + * + * Returns 0 on success -E2BIG if the resulting options string is too long. + */ +static int __init root_ceph_parse_options(char *incoming, char *exppath, + const size_t exppathlen) +{ + char *p; + int res = 0; + + /* + * Set the remote path + */ + p = strsep(&incoming, ","); + if (*p != '\0' && strcmp(p, "default") != 0) + strlcpy(exppath, p, exppathlen); + + /* + * @incoming now points to the rest of the string; if it + * contains something, append it to our root options buffer + */ + if (incoming != NULL && *incoming != '\0') { + size_t len = strlen(ceph_root_options); + size_t destlen = sizeof(ceph_root_options); + + if (len && ceph_root_options[len - 1] != ',') { + if (strlcat(ceph_root_options, ",", destlen) > destlen) + res = -E2BIG; + } + + if (strlcat(ceph_root_options, incoming, destlen) > destlen) + res = -E2BIG; + + } + return res; +} + +/* + * Parse CephFS server and directory information passed on the kernel + * command line. + * + * cephroot=[<server-ip>:]<root-dir>[,<cephfs-options>] + */ +static int __init ceph_root_setup(char *line) +{ + ROOT_DEV = Root_CEPH; + + strlcpy(ceph_root_params, line, sizeof(ceph_root_params)); + + /* + * Note: root_nfs_parse_addr() removes the server-ip from + * ceph_root_params, if it exists. + */ + root_ceph_server_addr = root_nfs_parse_addr(ceph_root_params); + + return 1; +} + +__setup("cephroot=", ceph_root_setup); + +/* + * ceph_root_data - Return mount device and data for CEPHROOT mount. + * + * @root_device: OUT: Address of string containing CEPHROOT device. + * @root_data: OUT: Address of string containing CEPHROOT mount options. + * + * Returns: 0 and sets @root_device and @root_data if successful. + * error code if unsuccessful. + */ +int __init ceph_root_data(char **root_device, char **root_data) +{ + char *tmp = NULL; + const size_t tmplen = sizeof(ceph_export_path); + int len; + int ret = -E2BIG; + + servaddr = root_ceph_server_addr; + if (servaddr == htonl(INADDR_NONE)) + return -ENOENT; + + tmp = kzalloc(tmplen, GFP_KERNEL); + if (tmp == NULL) + return -ENOMEM; + + if (ceph_root_params[0] != '\0') { + if (root_ceph_parse_options(ceph_root_params, tmp, tmplen)) + goto out; + } + + /* + * Set up ceph_root_device. This looks like: server:/path + * + * At this point, utsname()->nodename contains our local + * IP address or hostname, set by ipconfig. If "%s" exists + * in tmp, substitute the nodename, then shovel the whole + * mess into ceph_root_device. + */ + len = snprintf(ceph_export_path, sizeof(ceph_export_path), + tmp, utsname()->nodename); + if (len > (int)sizeof(ceph_export_path)) + goto out; + len = snprintf(ceph_root_device, sizeof(ceph_root_device), + "%pI4:%s", &servaddr, ceph_export_path); + if (len > (int)sizeof(ceph_root_device)) + goto out; + + pr_debug("Root-CEPH: Root device: %s\n", ceph_root_device); + pr_debug("Root-CEPH: Root options: %s\n", ceph_root_options); + *root_device = ceph_root_device; + *root_data = ceph_root_options; + + ret = 0; + +out: + kfree(tmp); + return ret; +} diff --git a/include/linux/ceph/ceph_root.h b/include/linux/ceph/ceph_root.h new file mode 100644 index 0000000..e6bae63 --- /dev/null +++ b/include/linux/ceph/ceph_root.h @@ -0,0 +1,10 @@ +/* + * Copyright (C) 2012 Codethink Ltd. <mark.doffman@codethink.co.uk> + * + * This file is released under the GPL v2 + * + * ceph_root.h + */ + +/* linux/fs/ceph/root.c */ +extern int ceph_root_data(char **root_device, char **root_data); /*__init*/ diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h index ed241aa..af6b182 100644 --- a/include/linux/root_dev.h +++ b/include/linux/root_dev.h @@ -16,6 +16,7 @@ enum { Root_SDA2 = MKDEV(SCSI_DISK0_MAJOR, 2), Root_HDC1 = MKDEV(IDE1_MAJOR, 1), Root_SR0 = MKDEV(SCSI_CDROM_MAJOR, 0), + Root_CEPH = MKDEV(UNNAMED_MAJOR, 254), }; extern dev_t ROOT_DEV; diff --git a/init/do_mounts.c b/init/do_mounts.c index 8e5addc..d075020 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -33,6 +33,8 @@ #include <linux/nfs_fs_sb.h> #include <linux/nfs_mount.h> +#include <linux/ceph/ceph_root.h> + #include "do_mounts.h" int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */ @@ -199,6 +201,7 @@ done: * a partition with a known unique id. * 8) <major>:<minor> major and minor number of the device separated by * a colon. + * 9) /dev/ceph represents Root_CEPH * * If name doesn't have fall into the categories above, we return (0,0). * block_class is used to check if something is a disk name. If the disk @@ -245,7 +248,9 @@ dev_t name_to_dev_t(char *name) res = Root_RAM0; if (strcmp(name, "ram") == 0) goto done; - + res = Root_CEPH; + if (strcmp(name, "ceph") == 0) + goto done; if (strlen(name) > 31) goto fail; strcpy(s, name); @@ -473,6 +478,22 @@ static int __init mount_nfs_root(void) } #endif +#ifdef CONFIG_ROOT_CEPH +static int __init mount_ceph_root(void) +{ + char *root_dev, *root_data; + + if (ceph_root_data(&root_dev, &root_data)) + return 0; + + if (do_mount_root(root_dev, "ceph", + root_mountflags, root_data)) + return 0; + + return 1; +} +#endif + #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD) void __init change_floppy(char *fmt, ...) { @@ -514,6 +535,15 @@ void __init mount_root(void) ROOT_DEV = Root_FD0; } #endif +#ifdef CONFIG_ROOT_CEPH + if (ROOT_DEV == Root_CEPH) { + if (mount_ceph_root()) + return; + + printk(KERN_ERR "VFS: Unable to mount root fs via CephFS, trying floppy.\n"); + ROOT_DEV = Root_FD0; + } +#endif #ifdef CONFIG_BLK_DEV_FD if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) { /* rd_doload is 2 for a dual initrd/ramload setup */