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Parse mount options just once and copy them to super block

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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 <sukadev@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Sukadev Bhattiprolu 2009-03-07 10:14:41 -08:00 committed by Al Viro
parent fdbf534866
commit 482984f06d
1 changed files with 22 additions and 78 deletions
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100
fs/devpts/inode.c
View file

@ -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 @@ static int new_pts_mount(struct file_system_type *fs_type, int flags,
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;
int error;
struct pts_mount_opts opts;
new = is_new_instance_mount(data);
if (new < 0)
return new;
memset(&opts, 0, sizeof(opts));
if (data) {
error = parse_mount_options(data, PARSE_MOUNT, &opts);
if (error)
return error;
}
if (new)
return new_pts_mount(fs_type, flags, data, mnt);
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