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1// SPDX-License-Identifier: GPL-2.0-only2#include <linux/export.h>3#include <linux/fs.h>4#include <linux/fs_stack.h>5 6/* does _NOT_ require i_mutex to be held.7 *8 * This function cannot be inlined since i_size_{read,write} is rather9 * heavy-weight on 32-bit systems10 */11void fsstack_copy_inode_size(struct inode *dst, struct inode *src)12{13 loff_t i_size;14 blkcnt_t i_blocks;15 16 /*17 * i_size_read() includes its own seqlocking and protection from18 * preemption (see include/linux/fs.h): we need nothing extra for19 * that here, and prefer to avoid nesting locks than attempt to keep20 * i_size and i_blocks in sync together.21 */22 i_size = i_size_read(src);23 24 /*25 * But on 32-bit, we ought to make an effort to keep the two halves of26 * i_blocks in sync despite SMP or PREEMPTION - though stat's27 * generic_fillattr() doesn't bother, and we won't be applying quotas28 * (where i_blocks does become important) at the upper level.29 *30 * We don't actually know what locking is used at the lower level;31 * but if it's a filesystem that supports quotas, it will be using32 * i_lock as in inode_add_bytes().33 */34 if (sizeof(i_blocks) > sizeof(long))35 spin_lock(&src->i_lock);36 i_blocks = src->i_blocks;37 if (sizeof(i_blocks) > sizeof(long))38 spin_unlock(&src->i_lock);39 40 /*41 * If CONFIG_SMP or CONFIG_PREEMPTION on 32-bit, it's vital for42 * fsstack_copy_inode_size() to hold some lock around43 * i_size_write(), otherwise i_size_read() may spin forever (see44 * include/linux/fs.h). We don't necessarily hold i_mutex when this45 * is called, so take i_lock for that case.46 *47 * And if on 32-bit, continue our effort to keep the two halves of48 * i_blocks in sync despite SMP or PREEMPTION: use i_lock for that case49 * too, and do both at once by combining the tests.50 *51 * There is none of this locking overhead in the 64-bit case.52 */53 if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))54 spin_lock(&dst->i_lock);55 i_size_write(dst, i_size);56 dst->i_blocks = i_blocks;57 if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long))58 spin_unlock(&dst->i_lock);59}60EXPORT_SYMBOL_GPL(fsstack_copy_inode_size);61 62/* copy all attributes */63void fsstack_copy_attr_all(struct inode *dest, const struct inode *src)64{65 dest->i_mode = src->i_mode;66 dest->i_uid = src->i_uid;67 dest->i_gid = src->i_gid;68 dest->i_rdev = src->i_rdev;69 inode_set_atime_to_ts(dest, inode_get_atime(src));70 inode_set_mtime_to_ts(dest, inode_get_mtime(src));71 inode_set_ctime_to_ts(dest, inode_get_ctime(src));72 dest->i_blkbits = src->i_blkbits;73 dest->i_flags = src->i_flags;74 set_nlink(dest, src->i_nlink);75}76EXPORT_SYMBOL_GPL(fsstack_copy_attr_all);77