* Re: [PATCH 1/3] 9p: add support for root file systems [not found] ` <20210505120748.8622-2-changbin.du@gmail.com> @ 2021-05-05 12:50 ` Dominique Martinet 2021-05-05 15:10 ` Enrico Weigelt, metux IT consult 2021-05-06 16:04 ` Changbin Du 0 siblings, 2 replies; 3+ messages in thread From: Dominique Martinet @ 2021-05-05 12:50 UTC (permalink / raw) To: Changbin Du Cc: Eric Van Hensbergen, Latchesar Ionkov, Jonathan Corbet, linux-doc, v9fs-developer, linux-fsdevel Why has this only been sent to direct maintainers and linux-doc@vger ? Please resend to at least v9fs-developer@sf, linux-fs@vger and whoever get_maintainer.pl deems appropriate for init/do_mounts.c changes (added the two lists to this mail) As a whole for the series: I'm personally not sure I'd encourage this, it can currently be done with an initrd if someone cares enough and if we're going to add all remote filesystems that way there's going to be no end to it. That being said, I'm not 100% opposed to it if there is demand; but I'll expect you to help with whatever bug reports people come up with using this option. Changbin Du wrote on Wed, May 05, 2021 at 08:07:46PM +0800: > diff --git a/fs/9p/v9fsroot.c b/fs/9p/v9fsroot.c > new file mode 100644 > index 000000000000..7dd91cc3814f > --- /dev/null > +++ b/fs/9p/v9fsroot.c > @@ -0,0 +1,64 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * SMB root file system support copy-paste error from fs/cifs/cifsroot.c > + * > + * Copyright (c) 2021 Changbin Du <changbin.du@gmail.com> > + */ > +#include <linux/init.h> > +#include <linux/fs.h> > +#include <linux/types.h> > +#include <linux/ctype.h> > +#include <linux/string.h> > +#include <linux/root_dev.h> > +#include <linux/kernel.h> > + > +static char root_dev[2048] __initdata = ""; > +static char root_opts[1024] __initdata = ""; > + > +/* v9fsroot=<path>[,options] */ > +static int __init v9fs_root_setup(char *line) > +{ > + char *s; > + int len; > + > + ROOT_DEV = Root_V9FS; > + > + if (strlen(line) >= 1) { > + /* make s point to ',' or '\0' at end of line */ > + s = strchrnul(line, ','); > + /* len is strlen(unc) + '\0' */ > + len = s - line + 1; > + if (len > sizeof(root_dev)) { > + printk(KERN_ERR "Root-V9FS: path too long\n"); 9p has its own p9_debug helper; it's a bit awkward because even P9_DEBUG_ERROR right now is not displayed by default so I'm not against pr_err or pr_warn for important messages (I'd like to replace all such messages by either at some point), but at least stick to pr_xyz(...) rather than printk(KERN_XYZ...) > + return 1; > + } > + strlcpy(root_dev, line, len); > + if (*s) { > + int n = snprintf(root_opts, > + sizeof(root_opts), "%s,%s", > + DEFAULT_MNT_OPTS, s + 1); Did you actually run with this? DEFAULT_MNT_OPTS is not defined here. > + if (n >= sizeof(root_opts)) { > + printk(KERN_ERR "Root-V9FS: mount options string too long\n"); > + root_opts[sizeof(root_opts)-1] = '\0'; > + return 1; > + } > + } > + } > + > + return 1; I'm also surprised this only ever returns 1, the cifs codes does the same but I'd be surprised the mount can work without a tag so there certainly should be some difference between working and not working? I'd also expect ROOT_DEV to only be set on success, this doesn't make sense to trigger 9p mounting mechanisms with something that can't be mounted, leading to a long timeout (5+10+15+30*2 seconds) before a hard error when the hard error can be given right away. > +} > + > +__setup("v9fsroot=", v9fs_root_setup); > + > +int __init v9fs_root_data(char **dev, char **opts) > +{ > + if (!root_dev[0]) { > + printk(KERN_ERR "Root-V9FS: no rootdev specified\n"); > + return -1; > + } > + > + *dev = root_dev; > + *opts = root_opts; > + > + return 0; > +} > diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h > index 4e78651371ba..becd0ee2ff87 100644 > --- a/include/linux/root_dev.h > +++ b/include/linux/root_dev.h > @@ -9,6 +9,7 @@ > enum { > Root_NFS = MKDEV(UNNAMED_MAJOR, 255), > Root_CIFS = MKDEV(UNNAMED_MAJOR, 254), > + Root_V9FS = MKDEV(UNNAMED_MAJOR, 253), > Root_RAM0 = MKDEV(RAMDISK_MAJOR, 0), > Root_RAM1 = MKDEV(RAMDISK_MAJOR, 1), > Root_FD0 = MKDEV(FLOPPY_MAJOR, 0), > diff --git a/init/do_mounts.c b/init/do_mounts.c > index a78e44ee6adb..60af89983a6b 100644 > --- a/init/do_mounts.c > +++ b/init/do_mounts.c > @@ -287,6 +287,8 @@ dev_t name_to_dev_t(const char *name) > return Root_NFS; > if (strcmp(name, "/dev/cifs") == 0) > return Root_CIFS; > + if (strcmp(name, "/dev/v9fs") == 0) > + return Root_V9FS; > if (strcmp(name, "/dev/ram") == 0) > return Root_RAM0; > #ifdef CONFIG_BLOCK > @@ -536,6 +538,43 @@ static int __init mount_cifs_root(void) > } > #endif > > +#ifdef CONFIG_9P_FS_ROOT > + > +extern int v9fs_root_data(char **dev, char **opts); > + > +#define V9FSROOT_TIMEOUT_MIN 5 > +#define V9FSROOT_TIMEOUT_MAX 30 > +#define V9FSROOT_RETRY_MAX 5 > + > +static int __init mount_v9fs_root(void) > +{ > + char *root_dev, *root_data; > + unsigned int timeout; > + int try, err; > + > + err = v9fs_root_data(&root_dev, &root_data); > + if (err != 0) > + return 0; > + > + timeout = V9FSROOT_TIMEOUT_MIN; > + for (try = 1; ; try++) { > + err = do_mount_root(root_dev, "9p", > + root_mountflags, root_data); > + if (err == 0) > + return 1; > + if (try > V9FSROOT_RETRY_MAX) > + break; > + > + /* Wait, in case the server refused us immediately */ > + ssleep(timeout); > + timeout <<= 1; > + if (timeout > V9FSROOT_TIMEOUT_MAX) > + timeout = V9FSROOT_TIMEOUT_MAX; > + } > + return 0; > +} > +#endif > + > void __init mount_root(void) > { > #ifdef CONFIG_ROOT_NFS > @@ -552,6 +591,13 @@ void __init mount_root(void) > return; > } > #endif > +#ifdef CONFIG_9P_FS_ROOT > + if (ROOT_DEV == Root_V9FS) { > + if (!mount_v9fs_root()) > + printk(KERN_ERR "VFS: Unable to mount root fs via 9p.\n"); > + return; > + } > +#endif > #ifdef CONFIG_BLOCK > { > int err = create_dev("/dev/root", ROOT_DEV); -- Dominique ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/3] 9p: add support for root file systems 2021-05-05 12:50 ` [PATCH 1/3] 9p: add support for root file systems Dominique Martinet @ 2021-05-05 15:10 ` Enrico Weigelt, metux IT consult 2021-05-06 16:04 ` Changbin Du 1 sibling, 0 replies; 3+ messages in thread From: Enrico Weigelt, metux IT consult @ 2021-05-05 15:10 UTC (permalink / raw) To: Dominique Martinet, Changbin Du Cc: Eric Van Hensbergen, Latchesar Ionkov, Jonathan Corbet, linux-doc, v9fs-developer, linux-fsdevel On 05.05.21 14:50, Dominique Martinet wrote: > As a whole for the series: I'm personally not sure I'd encourage this, > it can currently be done with an initrd if someone cares enough and if > we're going to add all remote filesystems that way there's going to be > no end to it. personally, I'd be *very* interested in that, especially for specially tailored vm grid workloads. please keep me in the loop. --mtx -- --- Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren GPG/PGP-Schlüssel zu. --- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287 ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/3] 9p: add support for root file systems 2021-05-05 12:50 ` [PATCH 1/3] 9p: add support for root file systems Dominique Martinet 2021-05-05 15:10 ` Enrico Weigelt, metux IT consult @ 2021-05-06 16:04 ` Changbin Du 1 sibling, 0 replies; 3+ messages in thread From: Changbin Du @ 2021-05-06 16:04 UTC (permalink / raw) To: Dominique Martinet Cc: Changbin Du, Eric Van Hensbergen, Latchesar Ionkov, Jonathan Corbet, linux-doc, v9fs-developer, linux-fsdevel, lkml On Wed, May 05, 2021 at 09:50:50PM +0900, Dominique Martinet wrote: > Why has this only been sent to direct maintainers and linux-doc@vger ? > Please resend to at least v9fs-developer@sf, linux-fs@vger and whoever > get_maintainer.pl deems appropriate for init/do_mounts.c changes > (added the two lists to this mail) > I made a typing mistake and then... > > As a whole for the series: I'm personally not sure I'd encourage this, > it can currently be done with an initrd if someone cares enough and if > we're going to add all remote filesystems that way there's going to be > no end to it. > > That being said, I'm not 100% opposed to it if there is demand; but I'll > expect you to help with whatever bug reports people come up with using > this option. > No problem, I can help with any issues related to this. It is worth doint this especially for some virtulizaion scenarioes. > > Changbin Du wrote on Wed, May 05, 2021 at 08:07:46PM +0800: > > diff --git a/fs/9p/v9fsroot.c b/fs/9p/v9fsroot.c > > new file mode 100644 > > index 000000000000..7dd91cc3814f > > --- /dev/null > > +++ b/fs/9p/v9fsroot.c > > @@ -0,0 +1,64 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * SMB root file system support > > copy-paste error from fs/cifs/cifsroot.c > Sorry, I'll fix it. > > + * > > + * Copyright (c) 2021 Changbin Du <changbin.du@gmail.com> > > + */ > > +#include <linux/init.h> > > +#include <linux/fs.h> > > +#include <linux/types.h> > > +#include <linux/ctype.h> > > +#include <linux/string.h> > > +#include <linux/root_dev.h> > > +#include <linux/kernel.h> > > + > > +static char root_dev[2048] __initdata = ""; > > +static char root_opts[1024] __initdata = ""; > > + > > +/* v9fsroot=<path>[,options] */ > > +static int __init v9fs_root_setup(char *line) > > +{ > > + char *s; > > + int len; > > + > > + ROOT_DEV = Root_V9FS; > > + > > + if (strlen(line) >= 1) { > > + /* make s point to ',' or '\0' at end of line */ > > + s = strchrnul(line, ','); > > + /* len is strlen(unc) + '\0' */ > > + len = s - line + 1; > > + if (len > sizeof(root_dev)) { > > + printk(KERN_ERR "Root-V9FS: path too long\n"); > > 9p has its own p9_debug helper; it's a bit awkward because even > P9_DEBUG_ERROR right now is not displayed by default so I'm not against > pr_err or pr_warn for important messages (I'd like to replace all such > messages by either at some point), but at least stick to pr_xyz(...) > rather than printk(KERN_XYZ...) > okay, will use pr_err() instead then. > > + return 1; > > + } > > + strlcpy(root_dev, line, len); > > + if (*s) { > > + int n = snprintf(root_opts, > > + sizeof(root_opts), "%s,%s", > > + DEFAULT_MNT_OPTS, s + 1); > > Did you actually run with this? DEFAULT_MNT_OPTS is not defined here. > oops, my bad that I forgot to test the latest change. > > + if (n >= sizeof(root_opts)) { > > + printk(KERN_ERR "Root-V9FS: mount options string too long\n"); > > + root_opts[sizeof(root_opts)-1] = '\0'; > > + return 1; > > + } > > + } > > + } > > + > > + return 1; > > I'm also surprised this only ever returns 1, the cifs codes does the > same but I'd be surprised the mount can work without a tag so there > certainly should be some difference between working and not working? > I think this returns 1 just means the "v9fsroot=" kernel parameter is handled so do not need further processing. But this doesn't mean the mount options can work. > I'd also expect ROOT_DEV to only be set on success, this doesn't make > sense to trigger 9p mounting mechanisms with something that can't be > mounted, leading to a long timeout (5+10+15+30*2 seconds) before a hard > error when the hard error can be given right away. > Sure, will only set ROOT_DEV after basic option checking. > > +} > > + > > +__setup("v9fsroot=", v9fs_root_setup); > > + > > +int __init v9fs_root_data(char **dev, char **opts) > > +{ > > + if (!root_dev[0]) { > > + printk(KERN_ERR "Root-V9FS: no rootdev specified\n"); > > + return -1; > > + } > > + > > + *dev = root_dev; > > + *opts = root_opts; > > + > > + return 0; > > +} > > diff --git a/include/linux/root_dev.h b/include/linux/root_dev.h > > index 4e78651371ba..becd0ee2ff87 100644 > > --- a/include/linux/root_dev.h > > +++ b/include/linux/root_dev.h > > @@ -9,6 +9,7 @@ > > enum { > > Root_NFS = MKDEV(UNNAMED_MAJOR, 255), > > Root_CIFS = MKDEV(UNNAMED_MAJOR, 254), > > + Root_V9FS = MKDEV(UNNAMED_MAJOR, 253), > > Root_RAM0 = MKDEV(RAMDISK_MAJOR, 0), > > Root_RAM1 = MKDEV(RAMDISK_MAJOR, 1), > > Root_FD0 = MKDEV(FLOPPY_MAJOR, 0), > > diff --git a/init/do_mounts.c b/init/do_mounts.c > > index a78e44ee6adb..60af89983a6b 100644 > > --- a/init/do_mounts.c > > +++ b/init/do_mounts.c > > @@ -287,6 +287,8 @@ dev_t name_to_dev_t(const char *name) > > return Root_NFS; > > if (strcmp(name, "/dev/cifs") == 0) > > return Root_CIFS; > > + if (strcmp(name, "/dev/v9fs") == 0) > > + return Root_V9FS; > > if (strcmp(name, "/dev/ram") == 0) > > return Root_RAM0; > > #ifdef CONFIG_BLOCK > > @@ -536,6 +538,43 @@ static int __init mount_cifs_root(void) > > } > > #endif > > > > +#ifdef CONFIG_9P_FS_ROOT > > + > > +extern int v9fs_root_data(char **dev, char **opts); > > + > > +#define V9FSROOT_TIMEOUT_MIN 5 > > +#define V9FSROOT_TIMEOUT_MAX 30 > > +#define V9FSROOT_RETRY_MAX 5 > > + > > +static int __init mount_v9fs_root(void) > > +{ > > + char *root_dev, *root_data; > > + unsigned int timeout; > > + int try, err; > > + > > + err = v9fs_root_data(&root_dev, &root_data); > > + if (err != 0) > > + return 0; > > + > > + timeout = V9FSROOT_TIMEOUT_MIN; > > + for (try = 1; ; try++) { > > + err = do_mount_root(root_dev, "9p", > > + root_mountflags, root_data); > > + if (err == 0) > > + return 1; > > + if (try > V9FSROOT_RETRY_MAX) > > + break; > > + > > + /* Wait, in case the server refused us immediately */ > > + ssleep(timeout); > > + timeout <<= 1; > > + if (timeout > V9FSROOT_TIMEOUT_MAX) > > + timeout = V9FSROOT_TIMEOUT_MAX; > > + } > > + return 0; > > +} > > +#endif > > + > > void __init mount_root(void) > > { > > #ifdef CONFIG_ROOT_NFS > > @@ -552,6 +591,13 @@ void __init mount_root(void) > > return; > > } > > #endif > > +#ifdef CONFIG_9P_FS_ROOT > > + if (ROOT_DEV == Root_V9FS) { > > + if (!mount_v9fs_root()) > > + printk(KERN_ERR "VFS: Unable to mount root fs via 9p.\n"); > > + return; > > + } > > +#endif > > #ifdef CONFIG_BLOCK > > { > > int err = create_dev("/dev/root", ROOT_DEV); > -- > Dominique -- Cheers, Changbin Du ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-05-06 16:04 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20210505120748.8622-1-changbin.du@gmail.com> [not found] ` <20210505120748.8622-2-changbin.du@gmail.com> 2021-05-05 12:50 ` [PATCH 1/3] 9p: add support for root file systems Dominique Martinet 2021-05-05 15:10 ` Enrico Weigelt, metux IT consult 2021-05-06 16:04 ` Changbin Du
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