forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
76 lines
2.5 KiB
76 lines
2.5 KiB
// 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 PREEMPTION - 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_PREEMPTION 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 PREEMPTION: 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);
|
|
|