77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
#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 if CONFIG_LBDAF (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 CONFIG_LBDAF (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);
|