Messages in this thread Patch in this message | | | Date | Mon, 11 May 2009 15:15:02 -0700 | From | Sukadev Bhattiprolu <> | Subject | Re: [v3][PATCH 5/5] Merge code for single andmultiple-instancemounts |
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Marc Dionne [marc.c.dionne@gmail.com] wrote: > On 05/07/2009 07:21 PM, Sukadev Bhattiprolu wrote: >> Er. I meant add following lines after the memset(). >> >> | opts->mode = DEVPTS_DEFAULT_MODE; >> | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; > > Adding those two lines (with . instead of ->) does fix the issue for me, > thanks. > > | > Of course we would still need to understand if/ > | > why this patch changes the settings. > > That particular patch changed things because the original memcpy in > new_pts_mount() did this: > > memcpy(&fsi->mount_opts, opts, sizeof(opts)); > > where opts was a pointer, not a structure. So only the first few bytes of > the blank opts actually got copied over. The patch moved this memcpy to > devpts_get_sb() and in the process fixed the sizeof error.
Here is a cleaner fix - When user space (/etc/rc.sysinit on RHEL5) mounts devpts, this problem might be masked since the mount system call could pass a non-NULL 'data' parmeter to devpts_get_sb().
I tested this patch by directly calling the system call mount() with a NULL data parameter. If you/Eric/Peter can confirm that this works for you, I will send this patch to Andrew.
Thanks, --- From 2f7746f4df78ff57125c4714f0cd64e739ccf804 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Date: Mon, 11 May 2009 13:11:11 -0700 Subject: [PATCH] devpts: Correctly set default options
devpts_get_sb() calls memset(0) to clear mount options and calls parse_mount_options() if user specified any mount options. The memset(0) is bogus since the 'mode' and 'ptmxmode' options are non-zero by default. parse_mount_options() restores options to default anyway and can properly deal with NULL mount options.
So in devpts_get_sb() remove memset(0) and call parse_mount_options() even for NULL mount options.
Bug reported by Eric Paris: http://lkml.org/lkml/2009/5/7/448.
Signed-off-by: Sukadev Bhattiprolu (sukadev@us.ibm.com) --- fs/devpts/inode.c | 18 ++++++++++++------ 1 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 63a4a59..b7a954e 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -90,6 +90,15 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode) #define PARSE_MOUNT 0 #define PARSE_REMOUNT 1 +/* + * parse_mount_options(): + * Set @opts to mount options specified in @data. If an option is not + * specified in @data, set it to its default value. The exception is + * 'newinstance' option which can only be set/cleared on a mount (i.e. + * cannot be changed during remount). + * + * Note: @data may be NULL (in which case all options are set to default). + */ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) { char *p; @@ -355,12 +364,9 @@ static int devpts_get_sb(struct file_system_type *fs_type, struct pts_mount_opts opts; struct super_block *s; - memset(&opts, 0, sizeof(opts)); - if (data) { - error = parse_mount_options(data, PARSE_MOUNT, &opts); - if (error) - return error; - } + error = parse_mount_options(data, PARSE_MOUNT, &opts); + if (error) + return error; if (opts.newinstance) s = sget(fs_type, NULL, set_anon_super, NULL);
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