diff options
Diffstat (limited to 'fs')
-rw-r--r-- | fs/overlayfs/super.c | 11 | ||||
-rw-r--r-- | fs/read_write.c | 29 | ||||
-rw-r--r-- | fs/super.c | 43 |
3 files changed, 63 insertions, 20 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 89182c4e2e30..bcf3965be819 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1303,6 +1303,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!oe) goto out_put_cred; + sb->s_magic = OVERLAYFS_SUPER_MAGIC; + sb->s_op = &ovl_super_operations; + sb->s_xattr = ovl_xattr_handlers; + sb->s_fs_info = ufs; + sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; + root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR)); if (!root_dentry) goto out_free_oe; @@ -1326,12 +1332,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); ovl_copyattr(realinode, d_inode(root_dentry)); - sb->s_magic = OVERLAYFS_SUPER_MAGIC; - sb->s_op = &ovl_super_operations; - sb->s_xattr = ovl_xattr_handlers; sb->s_root = root_dentry; - sb->s_fs_info = ufs; - sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; return 0; diff --git a/fs/read_write.c b/fs/read_write.c index 66215a7b17cf..190e0d362581 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -730,6 +730,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, /* A write operation does a read from user space and vice versa */ #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ) +/** + * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace + * into the kernel and check that it is valid. + * + * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE. + * @uvector: Pointer to the userspace array. + * @nr_segs: Number of elements in userspace array. + * @fast_segs: Number of elements in @fast_pointer. + * @fast_pointer: Pointer to (usually small on-stack) kernel array. + * @ret_pointer: (output parameter) Pointer to a variable that will point to + * either @fast_pointer, a newly allocated kernel array, or NULL, + * depending on which array was used. + * + * This function copies an array of &struct iovec of @nr_segs from + * userspace into the kernel and checks that each element is valid (e.g. + * it does not point to a kernel address or cause overflow by being too + * large, etc.). + * + * As an optimization, the caller may provide a pointer to a small + * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long + * (the size of this array, or 0 if unused, should be given in @fast_segs). + * + * @ret_pointer will always point to the array that was used, so the + * caller must take care not to call kfree() on it e.g. in case the + * @fast_pointer array was used and it was allocated on the stack. + * + * Return: The total number of bytes covered by the iovec array on success + * or a negative error code on error. + */ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, unsigned long nr_segs, unsigned long fast_segs, struct iovec *fast_pointer, diff --git a/fs/super.c b/fs/super.c index c2ff475c1711..c183835566c1 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1269,25 +1269,34 @@ EXPORT_SYMBOL(__sb_start_write); static void sb_wait_write(struct super_block *sb, int level) { percpu_down_write(sb->s_writers.rw_sem + level-1); - /* - * We are going to return to userspace and forget about this lock, the - * ownership goes to the caller of thaw_super() which does unlock. - * - * FIXME: we should do this before return from freeze_super() after we - * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super() - * should re-acquire these locks before s_op->unfreeze_fs(sb). However - * this leads to lockdep false-positives, so currently we do the early - * release right after acquire. - */ - percpu_rwsem_release(sb->s_writers.rw_sem + level-1, 0, _THIS_IP_); } -static void sb_freeze_unlock(struct super_block *sb) +/* + * We are going to return to userspace and forget about these locks, the + * ownership goes to the caller of thaw_super() which does unlock(). + */ +static void lockdep_sb_freeze_release(struct super_block *sb) +{ + int level; + + for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) + percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_); +} + +/* + * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb). + */ +static void lockdep_sb_freeze_acquire(struct super_block *sb) { int level; for (level = 0; level < SB_FREEZE_LEVELS; ++level) percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_); +} + +static void sb_freeze_unlock(struct super_block *sb) +{ + int level; for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) percpu_up_write(sb->s_writers.rw_sem + level); @@ -1379,10 +1388,11 @@ int freeze_super(struct super_block *sb) } } /* - * This is just for debugging purposes so that fs can warn if it - * sees write activity when frozen is set to SB_FREEZE_COMPLETE. + * For debugging purposes so that fs can warn if it sees write activity + * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). */ sb->s_writers.frozen = SB_FREEZE_COMPLETE; + lockdep_sb_freeze_release(sb); up_write(&sb->s_umount); return 0; } @@ -1399,7 +1409,7 @@ int thaw_super(struct super_block *sb) int error; down_write(&sb->s_umount); - if (sb->s_writers.frozen == SB_UNFROZEN) { + if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) { up_write(&sb->s_umount); return -EINVAL; } @@ -1409,11 +1419,14 @@ int thaw_super(struct super_block *sb) goto out; } + lockdep_sb_freeze_acquire(sb); + if (sb->s_op->unfreeze_fs) { error = sb->s_op->unfreeze_fs(sb); if (error) { printk(KERN_ERR "VFS:Filesystem thaw failed\n"); + lockdep_sb_freeze_release(sb); up_write(&sb->s_umount); return error; } |