From a9f184f02aa49d46c4c35311d93cbcd1c61149df Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Wed, 28 Jan 2009 16:57:12 -0800 Subject: devpts: Must release s_umount on error We should drop the ->s_umount mutex if an error occurs after the sget()/grab_super() call. This was introduced when adding support for multiple instances of devpts and noticed during a code review/reorg. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Al Viro --- fs/devpts/inode.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index bff4052b05e7..140b43144cd8 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -385,6 +385,7 @@ static int new_pts_mount(struct file_system_type *fs_type, int flags, fail: dput(mnt->mnt_sb->s_root); + up_write(&mnt->mnt_sb->s_umount); deactivate_super(mnt->mnt_sb); return err; } @@ -473,6 +474,7 @@ static int init_pts_mount(struct file_system_type *fs_type, int flags, err = mknod_ptmx(mnt->mnt_sb); if (err) { dput(mnt->mnt_sb->s_root); + up_write(&mnt->mnt_sb->s_umount); deactivate_super(mnt->mnt_sb); } -- cgit v1.2.2 From a3ec947c85ec339884b30ef6a08133e9311fdae1 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Wed, 4 Mar 2009 12:06:34 -0800 Subject: vfs: simple_set_mnt() should return void simple_set_mnt() is defined as returning 'int' but always returns 0. Callers assume simple_set_mnt() never fails and don't properly cleanup if it were to _ever_ fail. For instance, get_sb_single() and get_sb_nodev() should: up_write(sb->s_unmount); deactivate_super(sb); if simple_set_mnt() fails. Since simple_set_mnt() never fails, would be cleaner if it did not return anything. [akpm@linux-foundation.org: fix build] Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge Hallyn Cc: Al Viro Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/devpts/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 140b43144cd8..b0a76340a4cd 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -454,7 +454,8 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, s->s_flags |= MS_ACTIVE; } do_remount_sb(s, flags, data, 0); - return simple_set_mnt(mnt, s); + simple_set_mnt(mnt, s); + return 0; } /* -- cgit v1.2.2 From fdbf5348661ac9d519164d1489f30cc0384fda58 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Sat, 7 Mar 2009 10:16:20 -0800 Subject: Unroll essentials of do_remount_sb() into devpts On remount, devpts fs only needs to parse the mount options. Users cannot directly create/dirty files in /dev/pts so the MS_RDONLY flag and shrinking the dcache does not really apply to devpts. So effectively on remount, devpts only parses the mount options and updates these options in its super block. As such, we could replace do_remount_sb() call with a direct parse_mount_options(). Doing so enables subsequent patches to avoid parsing the mount options twice and simplify the code. Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge Hallyn Signed-off-by: Al Viro --- fs/devpts/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index b0a76340a4cd..fb4da9d89130 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -437,6 +437,8 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, void *data, struct vfsmount *mnt) { struct super_block *s; + struct pts_mount_opts *opts; + struct pts_fs_info *fsi; int error; s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); @@ -453,7 +455,10 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, } s->s_flags |= MS_ACTIVE; } - do_remount_sb(s, flags, data, 0); + fsi = DEVPTS_SB(s); + opts = &fsi->mount_opts; + parse_mount_options(data, PARSE_REMOUNT, opts); + simple_set_mnt(mnt, s); return 0; } -- cgit v1.2.2 From 482984f06df54d886995a4383d2f5bb85e3de945 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Sat, 7 Mar 2009 10:14:41 -0800 Subject: Parse mount options just once and copy them to super block Since all the mount option parsing is done in devpts, we could do it just once and pass it around in devpts functions and eventually store it in the super block. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Al Viro --- fs/devpts/inode.c | 100 ++++++++++++------------------------------------------ 1 file changed, 22 insertions(+), 78 deletions(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index fb4da9d89130..70013dd8ec70 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -321,61 +321,22 @@ static int compare_init_pts_sb(struct super_block *s, void *p) return 0; } -/* - * Safely parse the mount options in @data and update @opts. - * - * devpts ends up parsing options two times during mount, due to the - * two modes of operation it supports. The first parse occurs in - * devpts_get_sb() when determining the mode (single-instance or - * multi-instance mode). The second parse happens in devpts_remount() - * or new_pts_mount() depending on the mode. - * - * Parsing of options modifies the @data making subsequent parsing - * incorrect. So make a local copy of @data and parse it. - * - * Return: 0 On success, -errno on error - */ -static int safe_parse_mount_options(void *data, struct pts_mount_opts *opts) -{ - int rc; - void *datacp; - - if (!data) - return 0; - - /* Use kstrdup() ? */ - datacp = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!datacp) - return -ENOMEM; - - memcpy(datacp, data, PAGE_SIZE); - rc = parse_mount_options((char *)datacp, PARSE_MOUNT, opts); - kfree(datacp); - - return rc; -} - /* * Mount a new (private) instance of devpts. PTYs created in this * instance are independent of the PTYs in other devpts instances. */ static int new_pts_mount(struct file_system_type *fs_type, int flags, - void *data, struct vfsmount *mnt) + void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) { int err; struct pts_fs_info *fsi; - struct pts_mount_opts *opts; err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt); if (err) return err; fsi = DEVPTS_SB(mnt->mnt_sb); - opts = &fsi->mount_opts; - - err = parse_mount_options(data, PARSE_MOUNT, opts); - if (err) - goto fail; + memcpy(&fsi->mount_opts, opts, sizeof(opts)); err = mknod_ptmx(mnt->mnt_sb); if (err) @@ -390,28 +351,6 @@ fail: return err; } -/* - * Check if 'newinstance' mount option was specified in @data. - * - * Return: -errno on error (eg: invalid mount options specified) - * : 1 if 'newinstance' mount option was specified - * : 0 if 'newinstance' mount option was NOT specified - */ -static int is_new_instance_mount(void *data) -{ - int rc; - struct pts_mount_opts opts; - - if (!data) - return 0; - - rc = safe_parse_mount_options(data, &opts); - if (!rc) - rc = opts.newinstance; - - return rc; -} - /* * get_init_pts_sb() * @@ -434,10 +373,9 @@ static int is_new_instance_mount(void *data) * presence of the private namespace (i.e 'newinstance') super-blocks. */ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, - void *data, struct vfsmount *mnt) + void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) { struct super_block *s; - struct pts_mount_opts *opts; struct pts_fs_info *fsi; int error; @@ -455,11 +393,12 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, } s->s_flags |= MS_ACTIVE; } - fsi = DEVPTS_SB(s); - opts = &fsi->mount_opts; - parse_mount_options(data, PARSE_REMOUNT, opts); simple_set_mnt(mnt, s); + + fsi = DEVPTS_SB(mnt->mnt_sb); + memcpy(&fsi->mount_opts, opts, sizeof(opts)); + return 0; } @@ -469,11 +408,11 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, * kernel still allows multiple-instances. */ static int init_pts_mount(struct file_system_type *fs_type, int flags, - void *data, struct vfsmount *mnt) + void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) { int err; - err = get_init_pts_sb(fs_type, flags, data, mnt); + err = get_init_pts_sb(fs_type, flags, data, opts, mnt); if (err) return err; @@ -490,17 +429,22 @@ static int init_pts_mount(struct file_system_type *fs_type, int flags, static int devpts_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - int new; - - new = is_new_instance_mount(data); - if (new < 0) - return new; + int error; + struct pts_mount_opts opts; - if (new) - return new_pts_mount(fs_type, flags, data, mnt); + memset(&opts, 0, sizeof(opts)); + if (data) { + error = parse_mount_options(data, PARSE_MOUNT, &opts); + if (error) + return error; + } - return init_pts_mount(fs_type, flags, data, mnt); + if (opts.newinstance) + return new_pts_mount(fs_type, flags, data, &opts, mnt); + else + return init_pts_mount(fs_type, flags, data, &opts, mnt); } + #else /* * This supports only the legacy single-instance semantics (no -- cgit v1.2.2 From 945cf2c79f6fbb1b74e3b0ca08f48b6af56ad412 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Sat, 7 Mar 2009 10:11:41 -0800 Subject: Move common mknod_ptmx() calls into caller We create 'ptmx' node in both single-instance and multiple-instance mounts. So devpts_get_sb() can call mknod_ptmx() once rather than have both modes calling mknod_ptmx() separately. Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge Hallyn Signed-off-by: Al Viro --- fs/devpts/inode.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 70013dd8ec70..58b719006af1 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -338,17 +338,7 @@ static int new_pts_mount(struct file_system_type *fs_type, int flags, fsi = DEVPTS_SB(mnt->mnt_sb); memcpy(&fsi->mount_opts, opts, sizeof(opts)); - err = mknod_ptmx(mnt->mnt_sb); - if (err) - goto fail; - return 0; - -fail: - dput(mnt->mnt_sb->s_root); - up_write(&mnt->mnt_sb->s_umount); - deactivate_super(mnt->mnt_sb); - return err; } /* @@ -416,13 +406,6 @@ static int init_pts_mount(struct file_system_type *fs_type, int flags, if (err) return err; - err = mknod_ptmx(mnt->mnt_sb); - if (err) { - dput(mnt->mnt_sb->s_root); - up_write(&mnt->mnt_sb->s_umount); - deactivate_super(mnt->mnt_sb); - } - return err; } @@ -440,9 +423,24 @@ static int devpts_get_sb(struct file_system_type *fs_type, } if (opts.newinstance) - return new_pts_mount(fs_type, flags, data, &opts, mnt); + error = new_pts_mount(fs_type, flags, data, &opts, mnt); else - return init_pts_mount(fs_type, flags, data, &opts, mnt); + error = init_pts_mount(fs_type, flags, data, &opts, mnt); + + if (error) + return error; + + error = mknod_ptmx(mnt->mnt_sb); + if (error) + goto out_dput; + + return 0; + +out_dput: + dput(mnt->mnt_sb->s_root); + up_write(&mnt->mnt_sb->s_umount); + deactivate_super(mnt->mnt_sb); + return error; } #else -- cgit v1.2.2 From 289f00e225a6f60056644e0fd7e4081cb140c631 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Sat, 7 Mar 2009 10:12:06 -0800 Subject: Remove get_init_pts_sb() With mknod_ptmx() moved to devpts_get_sb(), init_pts_mount() becomes a wrapper around get_init_pts_sb(). Remove get_init_pts_sb() and fold code into init_pts_mount(). Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge Hallyn Signed-off-by: Al Viro --- fs/devpts/inode.c | 25 ++++++------------------- 1 file changed, 6 insertions(+), 19 deletions(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 58b719006af1..9c775fa4130f 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -342,7 +342,11 @@ static int new_pts_mount(struct file_system_type *fs_type, int flags, } /* - * get_init_pts_sb() + * init_pts_mount() + * + * Mount or remount the initial kernel mount of devpts. This type of + * mount maintains the legacy, single-instance semantics, while the + * kernel still allows multiple-instances. * * This interface is needed to support multiple namespace semantics in * devpts while preserving backward compatibility of the current 'single- @@ -362,7 +366,7 @@ static int new_pts_mount(struct file_system_type *fs_type, int flags, * consistently selects the 'single-namespace' superblock even in the * presence of the private namespace (i.e 'newinstance') super-blocks. */ -static int get_init_pts_sb(struct file_system_type *fs_type, int flags, +static int init_pts_mount(struct file_system_type *fs_type, int flags, void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) { struct super_block *s; @@ -392,23 +396,6 @@ static int get_init_pts_sb(struct file_system_type *fs_type, int flags, return 0; } -/* - * Mount or remount the initial kernel mount of devpts. This type of - * mount maintains the legacy, single-instance semantics, while the - * kernel still allows multiple-instances. - */ -static int init_pts_mount(struct file_system_type *fs_type, int flags, - void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) -{ - int err; - - err = get_init_pts_sb(fs_type, flags, data, opts, mnt); - if (err) - return err; - - return err; -} - static int devpts_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { -- cgit v1.2.2 From 1bd7903560f1f713e85188a5aaf4d2428b6c8b50 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Sat, 7 Mar 2009 10:12:32 -0800 Subject: Merge code for single and multiple-instance mounts new_pts_mount() (including the get_sb_nodev()), shares a lot of code with init_pts_mount(). The only difference between them is the 'test-super' function passed into sget(). Move all common code into devpts_get_sb() and remove the new_pts_mount() and init_pts_mount() functions, Changelog[v3]: [Serge Hallyn]: Remove unnecessary printk()s Changelog[v2]: (Christoph Hellwig): Merge code in 'do_pts_mount()' into devpts_get_sb() Signed-off-by: Sukadev Bhattiprolu Acked-by: Serge Hallyn Tested-by: Serge Hallyn Signed-off-by: Al Viro --- fs/devpts/inode.c | 113 +++++++++++++++++++----------------------------------- 1 file changed, 40 insertions(+), 73 deletions(-) (limited to 'fs/devpts/inode.c') diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 9c775fa4130f..63a4a59e4148 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -322,85 +322,38 @@ static int compare_init_pts_sb(struct super_block *s, void *p) } /* - * Mount a new (private) instance of devpts. PTYs created in this - * instance are independent of the PTYs in other devpts instances. - */ -static int new_pts_mount(struct file_system_type *fs_type, int flags, - void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) -{ - int err; - struct pts_fs_info *fsi; - - err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt); - if (err) - return err; - - fsi = DEVPTS_SB(mnt->mnt_sb); - memcpy(&fsi->mount_opts, opts, sizeof(opts)); - - return 0; -} - -/* - * init_pts_mount() + * devpts_get_sb() + * + * If the '-o newinstance' mount option was specified, mount a new + * (private) instance of devpts. PTYs created in this instance are + * independent of the PTYs in other devpts instances. + * + * If the '-o newinstance' option was not specified, mount/remount the + * initial kernel mount of devpts. This type of mount gives the + * legacy, single-instance semantics. * - * Mount or remount the initial kernel mount of devpts. This type of - * mount maintains the legacy, single-instance semantics, while the - * kernel still allows multiple-instances. + * The 'newinstance' option is needed to support multiple namespace + * semantics in devpts while preserving backward compatibility of the + * current 'single-namespace' semantics. i.e all mounts of devpts + * without the 'newinstance' mount option should bind to the initial + * kernel mount, like get_sb_single(). * - * This interface is needed to support multiple namespace semantics in - * devpts while preserving backward compatibility of the current 'single- - * namespace' semantics. i.e all mounts of devpts without the 'newinstance' - * mount option should bind to the initial kernel mount, like - * get_sb_single(). + * Mounts with 'newinstance' option create a new, private namespace. * - * Mounts with 'newinstance' option create a new private namespace. + * NOTE: * - * But for single-mount semantics, devpts cannot use get_sb_single(), + * For single-mount semantics, devpts cannot use get_sb_single(), * because get_sb_single()/sget() find and use the super-block from * the most recent mount of devpts. But that recent mount may be a * 'newinstance' mount and get_sb_single() would pick the newinstance * super-block instead of the initial super-block. - * - * This interface is identical to get_sb_single() except that it - * consistently selects the 'single-namespace' superblock even in the - * presence of the private namespace (i.e 'newinstance') super-blocks. */ -static int init_pts_mount(struct file_system_type *fs_type, int flags, - void *data, struct pts_mount_opts *opts, struct vfsmount *mnt) -{ - struct super_block *s; - struct pts_fs_info *fsi; - int error; - - s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); - if (IS_ERR(s)) - return PTR_ERR(s); - - if (!s->s_root) { - s->s_flags = flags; - error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); - if (error) { - up_write(&s->s_umount); - deactivate_super(s); - return error; - } - s->s_flags |= MS_ACTIVE; - } - - simple_set_mnt(mnt, s); - - fsi = DEVPTS_SB(mnt->mnt_sb); - memcpy(&fsi->mount_opts, opts, sizeof(opts)); - - return 0; -} - static int devpts_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { int error; struct pts_mount_opts opts; + struct super_block *s; memset(&opts, 0, sizeof(opts)); if (data) { @@ -410,23 +363,37 @@ static int devpts_get_sb(struct file_system_type *fs_type, } if (opts.newinstance) - error = new_pts_mount(fs_type, flags, data, &opts, mnt); + s = sget(fs_type, NULL, set_anon_super, NULL); else - error = init_pts_mount(fs_type, flags, data, &opts, mnt); + s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL); - if (error) - return error; + if (IS_ERR(s)) + return PTR_ERR(s); + + if (!s->s_root) { + s->s_flags = flags; + error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0); + if (error) + goto out_undo_sget; + s->s_flags |= MS_ACTIVE; + } + + simple_set_mnt(mnt, s); + + memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts)); - error = mknod_ptmx(mnt->mnt_sb); + error = mknod_ptmx(s); if (error) goto out_dput; return 0; out_dput: - dput(mnt->mnt_sb->s_root); - up_write(&mnt->mnt_sb->s_umount); - deactivate_super(mnt->mnt_sb); + dput(s->s_root); + +out_undo_sget: + up_write(&s->s_umount); + deactivate_super(s); return error; } -- cgit v1.2.2