1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/export.h>
4 #include <linux/fs_stack.h>
6 /* does _NOT_ require i_mutex to be held.
8 * This function cannot be inlined since i_size_{read,write} is rather
9 * heavy-weight on 32-bit systems
11 void fsstack_copy_inode_size(struct inode
*dst
, struct inode
*src
)
17 * i_size_read() includes its own seqlocking and protection from
18 * preemption (see include/linux/fs.h): we need nothing extra for
19 * that here, and prefer to avoid nesting locks than attempt to keep
20 * i_size and i_blocks in sync together.
22 i_size
= i_size_read(src
);
25 * But on 32-bit, we ought to make an effort to keep the two halves of
26 * i_blocks in sync despite SMP or PREEMPT - though stat's
27 * generic_fillattr() doesn't bother, and we won't be applying quotas
28 * (where i_blocks does become important) at the upper level.
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 using
32 * i_lock as in inode_add_bytes().
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
);
41 * If CONFIG_SMP or CONFIG_PREEMPT on 32-bit, it's vital for
42 * fsstack_copy_inode_size() to hold some lock around
43 * i_size_write(), otherwise i_size_read() may spin forever (see
44 * include/linux/fs.h). We don't necessarily hold i_mutex when this
45 * is called, so take i_lock for that case.
47 * And if on 32-bit, continue our effort to keep the two halves of
48 * i_blocks in sync despite SMP or PREEMPT: use i_lock for that case
49 * too, and do both at once by combining the tests.
51 * There is none of this locking overhead in the 64-bit case.
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
);
60 EXPORT_SYMBOL_GPL(fsstack_copy_inode_size
);
62 /* copy all attributes */
63 void fsstack_copy_attr_all(struct inode
*dest
, const struct inode
*src
)
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 dest
->i_atime
= src
->i_atime
;
70 dest
->i_mtime
= src
->i_mtime
;
71 dest
->i_ctime
= src
->i_ctime
;
72 dest
->i_blkbits
= src
->i_blkbits
;
73 dest
->i_flags
= src
->i_flags
;
74 set_nlink(dest
, src
->i_nlink
);
76 EXPORT_SYMBOL_GPL(fsstack_copy_attr_all
);