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ext4: zero out inline data using memset() instead of empty_zero_page 

Not all architectures (in particular, sparc64) have empty_zero_page.
So instead of copying from empty_zero_page, use memset to clear the
inline data by signalling to ext4_xattr_set_entry() via a magic
pointer value, EXT4_ZERO_ATTR_VALUE, which is defined by casting -1 to
a pointer.

This fixes a build failure on sparc64, and the memset() should be more
efficient than using memcpy() anyway.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2012-12-11 03:31:49 -05:00
parent 9a4c801947
commit bd9926e803
3 changed files with 18 additions and 7 deletions
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2
fs/ext4/inline.c
View File

@ -268,7 +268,7 @@ static int ext4_create_inline_data(handle_t *handle,
goto out;
if (len > EXT4_MIN_INLINE_DATA_SIZE) {
value = (void *)empty_zero_page;
value = EXT4_ZERO_XATTR_VALUE;
len -= EXT4_MIN_INLINE_DATA_SIZE;
} else {
value = "";

22
fs/ext4/xattr.c
View File

@ -628,9 +628,14 @@ ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
size. Just replace. */
s->here->e_value_size =
cpu_to_le32(i->value_len);
memset(val + size - EXT4_XATTR_PAD, 0,
EXT4_XATTR_PAD); /* Clear pad bytes. */
memcpy(val, i->value, i->value_len);
if (i->value == EXT4_ZERO_XATTR_VALUE) {
memset(val, 0, size);
} else {
/* Clear pad bytes first. */
memset(val + size - EXT4_XATTR_PAD, 0,
EXT4_XATTR_PAD);
memcpy(val, i->value, i->value_len);
}
return 0;
}
@ -669,9 +674,14 @@ ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
size_t size = EXT4_XATTR_SIZE(i->value_len);
void *val = s->base + min_offs - size;
s->here->e_value_offs = cpu_to_le16(min_offs - size);
memset(val + size - EXT4_XATTR_PAD, 0,
EXT4_XATTR_PAD); /* Clear the pad bytes. */
memcpy(val, i->value, i->value_len);
if (i->value == EXT4_ZERO_XATTR_VALUE) {
memset(val, 0, size);
} else {
/* Clear the pad bytes first. */
memset(val + size - EXT4_XATTR_PAD, 0,
EXT4_XATTR_PAD);
memcpy(val, i->value, i->value_len);
}
}
}
return 0;

1
fs/ext4/xattr.h
View File

@ -71,6 +71,7 @@ struct ext4_xattr_entry {
#define BFIRST(bh) ENTRY(BHDR(bh)+1)
#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
#define EXT4_ZERO_XATTR_VALUE ((void *)-1)
struct ext4_xattr_info {
int name_index;