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Date: Mon, 5 Aug 2013 10:34:52 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Zheng Liu <gnehzuil.liu@...il.com>
Cc: linux-ext4@...r.kernel.org, Zheng Liu <wenqing.lz@...bao.com>,
"Theodore Ts'o" <tytso@....edu>
Subject: Re: [PATCH v1 03/22] libext2fs: add functions to operate on extended
attribute
On Fri, Aug 02, 2013 at 05:49:30PM +0800, Zheng Liu wrote:
> From: Zheng Liu <wenqing.lz@...bao.com>
>
> We need to define some functions to operate extended attribute in order
> to support inline data.
>
> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
> lib/ext2fs/ext2_err.et.in | 3 +
> lib/ext2fs/ext2_ext_attr.h | 31 ++++++++
> lib/ext2fs/ext2fs.h | 9 +++
> lib/ext2fs/ext_attr.c | 186 ++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 229 insertions(+)
>
> diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
> index d20c6b7..7e6d6e5 100644
> --- a/lib/ext2fs/ext2_err.et.in
> +++ b/lib/ext2fs/ext2_err.et.in
> @@ -476,4 +476,7 @@ ec EXT2_ET_MMP_CSUM_INVALID,
> ec EXT2_ET_FILE_EXISTS,
> "Ext2 file already exists"
>
> +ec EXT2_ET_EXT_ATTR_CURRUPTED,
> + "Extended attribute currupted"
"corrupted".
(Or maybe shorten that to "corrupt"?)
--D
> +
> end
> diff --git a/lib/ext2fs/ext2_ext_attr.h b/lib/ext2fs/ext2_ext_attr.h
> index bbb0aaa..99ad849 100644
> --- a/lib/ext2fs/ext2_ext_attr.h
> +++ b/lib/ext2fs/ext2_ext_attr.h
> @@ -15,6 +15,10 @@
> /* Maximum number of references to one attribute block */
> #define EXT2_EXT_ATTR_REFCOUNT_MAX 1024
>
> +/* Name indexes */
> +#define EXT4_EXT_ATTR_INDEX_SYSTEM 7
> +#define EXT4_EXT_ATTR_SYSTEM_DATA "data"
> +
> struct ext2_ext_attr_header {
> __u32 h_magic; /* magic number for identification */
> __u32 h_refcount; /* reference count */
> @@ -25,6 +29,10 @@ struct ext2_ext_attr_header {
> __u32 h_reserved[3]; /* zero right now */
> };
>
> +struct ext2_ext_attr_ibody_header {
> + __u32 h_magic;
> +};
> +
> struct ext2_ext_attr_entry {
> __u8 e_name_len; /* length of name */
> __u8 e_name_index; /* attribute name index */
> @@ -57,6 +65,29 @@ struct ext2_ext_attr_entry {
> #define EXT2_XATTR_SIZE(size) \
> (((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
>
> +#define IHDR(inode) \
> + ((struct ext2_ext_attr_ibody_header *) \
> + ((char *)inode + \
> + EXT2_GOOD_OLD_INODE_SIZE + \
> + inode->i_extra_isize))
> +#define IFIRST(hdr) ((struct ext2_ext_attr_entry *)((hdr)+1))
> +#define EXT2_ZERO_EXT_ATTR_VALUE ((void *)-1)
> +
> +struct ext2_ext_attr_info {
> + int name_index;
> + const char *name;
> + const void *value;
> + size_t value_len;
> +};
> +
> +struct ext2_ext_attr_search {
> + struct ext2_ext_attr_entry *first;
> + void *base;
> + void *end;
> + struct ext2_ext_attr_entry *here;
> + int not_found;
> +};
> +
> #ifdef __KERNEL__
> # ifdef CONFIG_EXT2_FS_EXT_ATTR
> extern int ext2_get_ext_attr(struct inode *, const char *, char *, size_t, int);
> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> index 3346c00..8c30197 100644
> --- a/lib/ext2fs/ext2fs.h
> +++ b/lib/ext2fs/ext2fs.h
> @@ -1136,6 +1136,15 @@ extern errcode_t ext2fs_adjust_ea_refcount3(ext2_filsys fs, blk64_t blk,
> char *block_buf,
> int adjust, __u32 *newcount,
> ext2_ino_t inum);
> +extern errcode_t ext2fs_ext_attr_ibody_find(ext2_filsys fs,
> + struct ext2_inode_large *inode,
> + struct ext2_ext_attr_info *i,
> + struct ext2_ext_attr_search *s);
> +extern errcode_t ext2fs_ext_attr_find_entry(struct ext2_ext_attr_entry **pentry,
> + int name_index, const char *name,
> + size_t size, int sorted);
> +extern errcode_t ext2fs_ext_attr_set_entry(struct ext2_ext_attr_info *i,
> + struct ext2_ext_attr_search *s);
>
> /* extent.c */
> extern errcode_t ext2fs_extent_header_verify(void *ptr, int size);
> diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
> index 9649a14..6d55340 100644
> --- a/lib/ext2fs/ext_attr.c
> +++ b/lib/ext2fs/ext_attr.c
> @@ -186,3 +186,189 @@ errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
> return ext2fs_adjust_ea_refcount2(fs, blk, block_buf, adjust,
> newcount);
> }
> +
> +static errcode_t
> +ext2fs_ext_attr_check_names(struct ext2_ext_attr_entry *entry, void *end)
> +{
> + while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
> + struct ext2_ext_attr_entry *next = EXT2_EXT_ATTR_NEXT(entry);
> + if ((void *)next >= end)
> + return EXT2_ET_EXT_ATTR_CURRUPTED;
> + entry = next;
> + }
> + return 0;
> +}
> +
> +static inline errcode_t
> +ext2fs_ext_attr_check_entry(struct ext2_ext_attr_entry *entry, size_t size)
> +{
> + size_t value_size = entry->e_value_size;
> +
> + if (entry->e_value_block != 0 || value_size > size ||
> + entry->e_value_offs + value_size > size)
> + return EXT2_ET_EXT_ATTR_CURRUPTED;
> + return 0;
> +}
> +
> +errcode_t ext2fs_ext_attr_find_entry(struct ext2_ext_attr_entry **pentry,
> + int name_index, const char *name,
> + size_t size, int sorted)
> +{
> + struct ext2_ext_attr_entry *entry;
> + size_t name_len;
> + int cmp = 1;
> +
> + if (name == NULL)
> + return EXT2_ET_INVALID_ARGUMENT;
> + name_len = strlen(name);
> + for (entry = *pentry; !EXT2_EXT_IS_LAST_ENTRY(entry);
> + entry = EXT2_EXT_ATTR_NEXT(entry)) {
> + cmp = name_index - entry->e_name_index;
> + if (!cmp)
> + cmp = name_len - entry->e_name_len;
> + if (!cmp)
> + cmp = memcmp(name, EXT2_EXT_ATTR_NAME(entry),
> + name_len);
> + if (cmp <= 0 && (sorted || cmp == 0))
> + break;
> + }
> + *pentry = entry;
> + if (!cmp && ext2fs_ext_attr_check_entry(entry, size))
> + return EXT2_ET_EXT_ATTR_CURRUPTED;
> + return cmp ? ENODATA : 0;
> +}
> +
> +errcode_t ext2fs_ext_attr_ibody_find(ext2_filsys fs,
> + struct ext2_inode_large *inode,
> + struct ext2_ext_attr_info *i,
> + struct ext2_ext_attr_search *s)
> +{
> + struct ext2_ext_attr_ibody_header *header;
> + errcode_t error;
> +
> + if (inode->i_extra_isize == 0)
> + return 0;
> + header = IHDR(inode);
> + s->base = s->first = IFIRST(header);
> + s->here = s->first;
> + s->end = (char *)inode + EXT2_INODE_SIZE(fs->super);
> +
> + error = ext2fs_ext_attr_check_names(IFIRST(header), s->end);
> + if (error)
> + return error;
> + /* Find the named attribute. */
> + error = ext2fs_ext_attr_find_entry(&s->here, i->name_index,
> + i->name, (char *)s->end -
> + (char *)s->base, 0);
> + if (error && error != ENODATA)
> + return error;
> + s->not_found = error;
> + return 0;
> +}
> +
> +errcode_t ext2fs_ext_attr_set_entry(struct ext2_ext_attr_info *i,
> + struct ext2_ext_attr_search *s)
> +{
> + struct ext2_ext_attr_entry *last;
> + size_t freesize, min_offs = (char *)s->end - (char *)s->base;
> + size_t name_len = strlen(i->name);
> +
> + /* Compute min_offs and last. */
> + last = s->first;
> + for (; !EXT2_EXT_IS_LAST_ENTRY(last); last = EXT2_EXT_ATTR_NEXT(last)) {
> + if (!last->e_value_block && last->e_value_size) {
> + size_t offs = last->e_value_offs;
> + if (offs < min_offs)
> + min_offs = offs;
> + }
> + }
> + freesize = min_offs - ((char *)last - (char *)s->base) - sizeof(__u32);
> + if (!s->not_found) {
> + if (!s->here->e_value_block && s->here->e_value_size) {
> + size_t size = s->here->e_value_size;
> + freesize += EXT2_EXT_ATTR_SIZE(size);
> + }
> + freesize += EXT2_EXT_ATTR_LEN(name_len);
> + }
> + if (i->value) {
> + if (freesize < EXT2_EXT_ATTR_SIZE(i->value_len) ||
> + freesize < EXT2_EXT_ATTR_LEN(name_len) +
> + EXT2_EXT_ATTR_SIZE(i->value_len))
> + return ENOSPC;
> + }
> +
> + if (i->value && s->not_found) {
> + /* Insert the new name. */
> + size_t size = EXT2_EXT_ATTR_LEN(name_len);
> + size_t rest = (char *)last - (char *)s->here + sizeof(__u32);
> + memmove((char *)s->here + size, s->here, rest);
> + memset(s->here, 0, size);
> + s->here->e_name_index = i->name_index;
> + s->here->e_name_len = name_len;
> + memcpy(EXT2_EXT_ATTR_NAME(s->here), i->name, name_len);
> + } else {
> + if (!s->here->e_value_block && s->here->e_value_size) {
> + char *first_val = (char *) s->base + min_offs;
> + size_t offs = s->here->e_value_offs;
> + char *val = (char *)s->base + offs;
> + size_t size = EXT2_EXT_ATTR_SIZE(s->here->e_value_size);
> +
> + if (i->value && size == EXT2_EXT_ATTR_SIZE(i->value_len)) {
> + /* The old and the new value have the same
> + * size. Just replace. */
> + s->here->e_value_size = i->value_len;
> + if (i->value == EXT2_ZERO_EXT_ATTR_VALUE) {
> + memset(val, 0, size);
> + } else {
> + memset(val + size - EXT2_EXT_ATTR_PAD, 0,
> + EXT2_EXT_ATTR_PAD);
> + memcpy(val, i->value, i->value_len);
> + }
> + return 0;
> + }
> +
> + /* Remove the old value. */
> + memmove(first_val + size, first_val, val - first_val);
> + memset(first_val, 0, size);
> + s->here->e_value_size = 0;
> + s->here->e_value_offs = 0;
> + min_offs += size;
> +
> + /* Adjust all value offsets. */
> + last = s->first;
> + while (!EXT2_EXT_IS_LAST_ENTRY(last)) {
> + size_t o = last->e_value_offs;
> + if (!last->e_value_block &&
> + last->e_value_size && o < offs)
> + last->e_value_offs = o + size;
> + last = EXT2_EXT_ATTR_NEXT(last);
> + }
> + }
> + if (!i->value) {
> + /* Remove the old name. */
> + size_t size = EXT2_EXT_ATTR_LEN(name_len);
> + last = (struct ext2_ext_attr_entry *)last - size;
> + memmove(s->here, (char *)s->here + size,
> + (char *)last - (char *)s->here + sizeof(__u32));
> + memset(last, 0, size);
> + }
> + }
> +
> + if (i->value) {
> + /* Insert the new value. */
> + s->here->e_value_size = i->value_len;
> + if (i->value_len) {
> + size_t size = EXT2_EXT_ATTR_SIZE(i->value_len);
> + char *val = (char *)s->base + min_offs - size;
> + s->here->e_value_offs = min_offs - size;
> + if (i->value == EXT2_ZERO_EXT_ATTR_VALUE) {
> + memset(val, 0, size);
> + } else {
> + memset(val + size - EXT2_EXT_ATTR_PAD, 0,
> + EXT2_EXT_ATTR_PAD);
> + memcpy(val, i->value, i->value_len);
> + }
> + }
> + }
> + return 0;
> +}
> --
> 1.7.9.7
>
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