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Message-ID: <20131012055154.GA6377@gmail.com>
Date: Sat, 12 Oct 2013 13:51:54 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: "Darrick J. Wong" <darrick.wong@...cle.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, Oct 11, 2013 at 03:51:15PM -0700, Darrick J. Wong wrote:
> 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"
> > +
> > 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;
>
> Huh. It just occurred to me (yes, after three months, sorry...) that your
> patchset doesn't deal with EAs that live in a separate block. For the purposes
> of inline_data I suppose that's sufficient, but if we're going to add an API to
> mess with EAs, we ought to be able to handle all of a file's EAs.
>
> The implementation that I wrote for fuse2fs does this, but it has no facility
> to ensure that the inline data ends up in the ibody and not the EA block.
> Though really, they're written out in array order, so it wouldn't be difficult
> to sort before writing, or use some knapsack variant.
Sorry, I still havn't had a chance to take a closer look at your patch
set for e2fsprogs. I will review it ASAP.
>
> I think I might be drifting towards the idea of attaching your patch series to
> the end of mine, but as yours is already in -pu I'm open to discussing how to
> reconcile our implementations.
I agree with you that we need to reconcile our implementation. I was
wondering if we really need to add all APIs for EAs in e2fsprogs when I
added these functions. But now it seems that we do need them.
>
> I _do_ like the comments you added to ext2fs_ext_attr_set_entry() though. :)
Yes, there is no any difficulty to add this API. :-)
Regards,
- Zheng
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