| // SPDX-License-Identifier: GPL-2.0-only |
| #include <linux/export.h> |
| #include <linux/fs.h> |
| #include <linux/fs_stack.h> |
| |
| /* does _NOT_ require i_mutex to be held. |
| * |
| * This function cannot be inlined since i_size_{read,write} is rather |
| * heavy-weight on 32-bit systems |
| */ |
| void fsstack_copy_inode_size(struct inode *dst, struct inode *src) |
| { |
| loff_t i_size; |
| blkcnt_t i_blocks; |
| |
| /* |
| * i_size_read() includes its own seqlocking and protection from |
| * preemption (see include/linux/fs.h): we need nothing extra for |
| * that here, and prefer to avoid nesting locks than attempt to keep |
| * i_size and i_blocks in sync together. |
| */ |
| i_size = i_size_read(src); |
| |
| /* |
| * But on 32-bit, we ought to make an effort to keep the two halves of |
| * i_blocks in sync despite SMP or PREEMPT - though stat's |
| * generic_fillattr() doesn't bother, and we won't be applying quotas |
| * (where i_blocks does become important) at the upper level. |
| * |
| * We don't actually know what locking is used at the lower level; |
| * but if it's a filesystem that supports quotas, it will be using |
| * i_lock as in inode_add_bytes(). |
| */ |
| if (sizeof(i_blocks) > sizeof(long)) |
| spin_lock(&src->i_lock); |
| i_blocks = src->i_blocks; |
| if (sizeof(i_blocks) > sizeof(long)) |
| spin_unlock(&src->i_lock); |
| |
| /* |
| * If CONFIG_SMP or CONFIG_PREEMPT on 32-bit, it's vital for |
| * fsstack_copy_inode_size() to hold some lock around |
| * i_size_write(), otherwise i_size_read() may spin forever (see |
| * include/linux/fs.h). We don't necessarily hold i_mutex when this |
| * is called, so take i_lock for that case. |
| * |
| * And if on 32-bit, continue our effort to keep the two halves of |
| * i_blocks in sync despite SMP or PREEMPT: use i_lock for that case |
| * too, and do both at once by combining the tests. |
| * |
| * There is none of this locking overhead in the 64-bit case. |
| */ |
| if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) |
| spin_lock(&dst->i_lock); |
| i_size_write(dst, i_size); |
| dst->i_blocks = i_blocks; |
| if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) |
| spin_unlock(&dst->i_lock); |
| } |
| EXPORT_SYMBOL_GPL(fsstack_copy_inode_size); |
| |
| /* copy all attributes */ |
| void fsstack_copy_attr_all(struct inode *dest, const struct inode *src) |
| { |
| dest->i_mode = src->i_mode; |
| dest->i_uid = src->i_uid; |
| dest->i_gid = src->i_gid; |
| dest->i_rdev = src->i_rdev; |
| dest->i_atime = src->i_atime; |
| dest->i_mtime = src->i_mtime; |
| dest->i_ctime = src->i_ctime; |
| dest->i_blkbits = src->i_blkbits; |
| dest->i_flags = src->i_flags; |
| set_nlink(dest, src->i_nlink); |
| } |
| EXPORT_SYMBOL_GPL(fsstack_copy_attr_all); |