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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 <[email protected]>
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Al Viro
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Apr 1, 2009
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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); | ||
| } |
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