diff options
author | Al Viro <viro@zeniv.linux.org.uk> | 2009-03-30 01:00:13 +0200 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-04-01 05:00:26 +0200 |
commit | 3e93cd671813e204c258f1e6c797959920cf7772 (patch) | |
tree | a1e0b2d2da7d296cc1c53be9cd6efa5b94b01b5c /fs/fs_struct.c | |
parent | Get rid of bumping fs_struct refcount in pivot_root(2) (diff) | |
download | linux-3e93cd671813e204c258f1e6c797959920cf7772.tar.xz linux-3e93cd671813e204c258f1e6c797959920cf7772.zip |
Take fs_struct handling to new file (fs/fs_struct.c)
Pure code move; two new helper functions for nfsd and daemonize
(unshare_fs_struct() and daemonize_fs_struct() resp.; for now -
the same code as used to be in callers). unshare_fs_struct()
exported (for nfsd, as copy_fs_struct()/exit_fs() used to be),
copy_fs_struct() and exit_fs() don't need exports anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/fs_struct.c')
-rw-r--r-- | fs/fs_struct.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/fs/fs_struct.c b/fs/fs_struct.c new file mode 100644 index 000000000000..36e0a123bbf3 --- /dev/null +++ b/fs/fs_struct.c @@ -0,0 +1,141 @@ +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/fs.h> +#include <linux/path.h> +#include <linux/slab.h> + +/* + * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values. + * It can block. + */ +void set_fs_root(struct fs_struct *fs, struct path *path) +{ + struct path old_root; + + write_lock(&fs->lock); + old_root = fs->root; + fs->root = *path; + path_get(path); + write_unlock(&fs->lock); + if (old_root.dentry) + path_put(&old_root); +} + +/* + * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values. + * It can block. + */ +void set_fs_pwd(struct fs_struct *fs, struct path *path) +{ + struct path old_pwd; + + write_lock(&fs->lock); + old_pwd = fs->pwd; + fs->pwd = *path; + path_get(path); + write_unlock(&fs->lock); + + if (old_pwd.dentry) + path_put(&old_pwd); +} + +void chroot_fs_refs(struct path *old_root, struct path *new_root) +{ + struct task_struct *g, *p; + struct fs_struct *fs; + int count = 0; + + read_lock(&tasklist_lock); + do_each_thread(g, p) { + task_lock(p); + fs = p->fs; + if (fs) { + write_lock(&fs->lock); + if (fs->root.dentry == old_root->dentry + && fs->root.mnt == old_root->mnt) { + path_get(new_root); + fs->root = *new_root; + count++; + } + if (fs->pwd.dentry == old_root->dentry + && fs->pwd.mnt == old_root->mnt) { + path_get(new_root); + fs->pwd = *new_root; + count++; + } + write_unlock(&fs->lock); + } + task_unlock(p); + } while_each_thread(g, p); + read_unlock(&tasklist_lock); + while (count--) + path_put(old_root); +} + +void put_fs_struct(struct fs_struct *fs) +{ + /* No need to hold fs->lock if we are killing it */ + if (atomic_dec_and_test(&fs->count)) { + path_put(&fs->root); + path_put(&fs->pwd); + kmem_cache_free(fs_cachep, fs); + } +} + +void exit_fs(struct task_struct *tsk) +{ + struct fs_struct * fs = tsk->fs; + + if (fs) { + task_lock(tsk); + tsk->fs = NULL; + task_unlock(tsk); + put_fs_struct(fs); + } +} + +struct fs_struct *copy_fs_struct(struct fs_struct *old) +{ + struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); + /* We don't need to lock fs - think why ;-) */ + if (fs) { + atomic_set(&fs->count, 1); + rwlock_init(&fs->lock); + fs->umask = old->umask; + read_lock(&old->lock); + fs->root = old->root; + path_get(&old->root); + fs->pwd = old->pwd; + path_get(&old->pwd); + read_unlock(&old->lock); + } + return fs; +} + +int unshare_fs_struct(void) +{ + struct fs_struct *fsp = copy_fs_struct(current->fs); + if (!fsp) + return -ENOMEM; + exit_fs(current); + current->fs = fsp; + return 0; +} +EXPORT_SYMBOL_GPL(unshare_fs_struct); + +/* to be mentioned only in INIT_TASK */ +struct fs_struct init_fs = { + .count = ATOMIC_INIT(1), + .lock = __RW_LOCK_UNLOCKED(init_fs.lock), + .umask = 0022, +}; + +void daemonize_fs_struct(void) +{ + struct fs_struct *fs; + + exit_fs(current); /* current->fs->count--; */ + fs = &init_fs; + current->fs = fs; + atomic_inc(&fs->count); +} |