From 9e7fdd25b21ebf50713dfb7702af57c270e5572a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 30 Mar 2010 11:31:24 -0700 Subject: sysfs: Basic support for multiple super blocks Add all of the necessary bioler plate to support multiple superblocks in sysfs. Signed-off-by: Eric W. Biederman Acked-by: Serge Hallyn Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/mount.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 56 insertions(+), 2 deletions(-) (limited to 'fs/sysfs/mount.c') diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 776137828dca..db0b1f2138af 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -72,16 +72,70 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent) return 0; } +static int sysfs_test_super(struct super_block *sb, void *data) +{ + struct sysfs_super_info *sb_info = sysfs_info(sb); + struct sysfs_super_info *info = data; + int found = 1; + return found; +} + +static int sysfs_set_super(struct super_block *sb, void *data) +{ + int error; + error = set_anon_super(sb, data); + if (!error) + sb->s_fs_info = data; + return error; +} + static int sysfs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt); + struct sysfs_super_info *info; + struct super_block *sb; + int error; + + error = -ENOMEM; + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) + goto out; + sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); + if (IS_ERR(sb) || sb->s_fs_info != info) + kfree(info); + if (IS_ERR(sb)) { + kfree(info); + error = PTR_ERR(sb); + goto out; + } + if (!sb->s_root) { + sb->s_flags = flags; + error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); + if (error) { + deactivate_locked_super(sb); + goto out; + } + sb->s_flags |= MS_ACTIVE; + } + + simple_set_mnt(mnt, sb); + error = 0; +out: + return error; +} + +static void sysfs_kill_sb(struct super_block *sb) +{ + struct sysfs_super_info *info = sysfs_info(sb); + + kill_anon_super(sb); + kfree(info); } static struct file_system_type sysfs_fs_type = { .name = "sysfs", .get_sb = sysfs_get_sb, - .kill_sb = kill_anon_super, + .kill_sb = sysfs_kill_sb, }; int __init sysfs_init(void) -- cgit v1.2.3 From ba514a57f5c38d9d79ea15e75059e07f49238726 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 30 Mar 2010 16:50:26 -0700 Subject: sysfs: Remove double free sysfs_get_sb Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/mount.c | 1 - 1 file changed, 1 deletion(-) (limited to 'fs/sysfs/mount.c') diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index db0b1f2138af..50e4fb6a7403 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -104,7 +104,6 @@ static int sysfs_get_sb(struct file_system_type *fs_type, if (IS_ERR(sb) || sb->s_fs_info != info) kfree(info); if (IS_ERR(sb)) { - kfree(info); error = PTR_ERR(sb); goto out; } -- cgit v1.2.3 From 3ff195b011d7decf501a4d55aeed312731094796 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 30 Mar 2010 11:31:26 -0700 Subject: sysfs: Implement sysfs tagged directory support. The problem. When implementing a network namespace I need to be able to have multiple network devices with the same name. Currently this is a problem for /sys/class/net/*, /sys/devices/virtual/net/*, and potentially a few other directories of the form /sys/ ... /net/*. What this patch does is to add an additional tag field to the sysfs dirent structure. For directories that should show different contents depending on the context such as /sys/class/net/, and /sys/devices/virtual/net/ this tag field is used to specify the context in which those directories should be visible. Effectively this is the same as creating multiple distinct directories with the same name but internally to sysfs the result is nicer. I am calling the concept of a single directory that looks like multiple directories all at the same path in the filesystem tagged directories. For the networking namespace the set of directories whose contents I need to filter with tags can depend on the presence or absence of hotplug hardware or which modules are currently loaded. Which means I need a simple race free way to setup those directories as tagged. To achieve a reace free design all tagged directories are created and managed by sysfs itself. Users of this interface: - define a type in the sysfs_tag_type enumeration. - call sysfs_register_ns_types with the type and it's operations - sysfs_exit_ns when an individual tag is no longer valid - Implement mount_ns() which returns the ns of the calling process so we can attach it to a sysfs superblock. - Implement ktype.namespace() which returns the ns of a syfs kobject. Everything else is left up to sysfs and the driver layer. For the network namespace mount_ns and namespace() are essentially one line functions, and look to remain that. Tags are currently represented a const void * pointers as that is both generic, prevides enough information for equality comparisons, and is trivial to create for current users, as it is just the existing namespace pointer. The work needed in sysfs is more extensive. At each directory or symlink creating I need to check if the directory it is being created in is a tagged directory and if so generate the appropriate tag to place on the sysfs_dirent. Likewise at each symlink or directory removal I need to check if the sysfs directory it is being removed from is a tagged directory and if so figure out which tag goes along with the name I am deleting. Currently only directories which hold kobjects, and symlinks are supported. There is not enough information in the current file attribute interfaces to give us anything to discriminate on which makes it useless, and there are no potential users which makes it an uninteresting problem to solve. Signed-off-by: Eric W. Biederman Signed-off-by: Benjamin Thery Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/mount.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) (limited to 'fs/sysfs/mount.c') diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 50e4fb6a7403..1afa32ba242c 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -35,7 +35,7 @@ static const struct super_operations sysfs_ops = { struct sysfs_dirent sysfs_root = { .s_name = "", .s_count = ATOMIC_INIT(1), - .s_flags = SYSFS_DIR, + .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT), .s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, .s_ino = 1, }; @@ -76,7 +76,13 @@ static int sysfs_test_super(struct super_block *sb, void *data) { struct sysfs_super_info *sb_info = sysfs_info(sb); struct sysfs_super_info *info = data; + enum kobj_ns_type type; int found = 1; + + for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) { + if (sb_info->ns[type] != info->ns[type]) + found = 0; + } return found; } @@ -93,6 +99,7 @@ static int sysfs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { struct sysfs_super_info *info; + enum kobj_ns_type type; struct super_block *sb; int error; @@ -100,6 +107,10 @@ static int sysfs_get_sb(struct file_system_type *fs_type, info = kzalloc(sizeof(*info), GFP_KERNEL); if (!info) goto out; + + for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) + info->ns[type] = kobj_ns_current(type); + sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info); if (IS_ERR(sb) || sb->s_fs_info != info) kfree(info); @@ -137,6 +148,26 @@ static struct file_system_type sysfs_fs_type = { .kill_sb = sysfs_kill_sb, }; +void sysfs_exit_ns(enum kobj_ns_type type, const void *ns) +{ + struct super_block *sb; + + mutex_lock(&sysfs_mutex); + spin_lock(&sb_lock); + list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) { + struct sysfs_super_info *info = sysfs_info(sb); + /* Ignore superblocks that are in the process of unmounting */ + if (sb->s_count <= S_BIAS) + continue; + /* Ignore superblocks with the wrong ns */ + if (info->ns[type] != ns) + continue; + info->ns[type] = NULL; + } + spin_unlock(&sb_lock); + mutex_unlock(&sysfs_mutex); +} + int __init sysfs_init(void) { int err = -ENOMEM; -- cgit v1.2.3 From 68d75ed4b84a0806ecd4bc14da4759713b23a532 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 18 May 2010 12:58:33 -0700 Subject: sysfs: Remove usage of S_BIAS to avoid merge conflict with the vfs tree In Al's latest vfs tree the code is reworked and S_BIAS has been removed. It turns out that checking to see if a super block is in the middle of an unmount in sysfs_exit_ns is unnecessary because we remove the super_block from the s_supers/s_instances list before struct sysfs_super_info pointed to by sb->s_fs_info is freed. For now just delete the unnecessary check to see if a superblock is in the middle of an unmount, it isn't necessary with or without Al's changes and it just causes a needless conflict. Reported-by: Stephen Rothwell Cc: Al Viro Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/mount.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'fs/sysfs/mount.c') diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 1afa32ba242c..281c0c9bc39f 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -138,6 +138,9 @@ static void sysfs_kill_sb(struct super_block *sb) { struct sysfs_super_info *info = sysfs_info(sb); + /* Remove the superblock from fs_supers/s_instances + * so we can't find it, before freeing sysfs_super_info. + */ kill_anon_super(sb); kfree(info); } @@ -156,9 +159,11 @@ void sysfs_exit_ns(enum kobj_ns_type type, const void *ns) spin_lock(&sb_lock); list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) { struct sysfs_super_info *info = sysfs_info(sb); - /* Ignore superblocks that are in the process of unmounting */ - if (sb->s_count <= S_BIAS) - continue; + /* + * If we see a superblock on the fs_supers/s_instances + * list the unmount has not completed and sb->s_fs_info + * points to a valid struct sysfs_super_info. + */ /* Ignore superblocks with the wrong ns */ if (info->ns[type] != ns) continue; -- cgit v1.2.3