[RFC] erofs-utils: on-disk extent format for blocks.
Pratik Shinde
pratikshinde320 at gmail.com
Mon Dec 30 18:16:43 AEDT 2019
Okay. Apologies. I think we already have erofs_blknr() to do this job. I
can use that.:)
--Pratik.
On Mon, Dec 30, 2019 at 12:34 PM Pratik Shinde <pratikshinde320 at gmail.com>
wrote:
> Thanks got it.
>
> Then we can use LOG_BLOCK_SIZE , to get block no. for corresponding file
> offset.
>
> --Pratik.
>
> On Mon, Dec 30, 2019 at 12:19 PM Gao Xiang <gaoxiang25 at huawei.com> wrote:
>
>> On Mon, Dec 30, 2019 at 11:49:55AM +0530, Pratik Shinde wrote:
>> > Gao,
>> >
>> > Okay, I will rename the 'size' variables accordingly.
>> > The 'S_SHIFT' gives the logical block number inside file. I am using it
>> to
>> > assign logical block no.
>> > to extents.
>>
>> S_SHIFT is used to transfer between i_mode and filetype, see:
>> https://elixir.bootlin.com/linux/latest/source/fs/ext4/ext4.h#L3196
>>
>> IMO, which is not the above meaning, how about using EROFS_BLKSIZ
>> instead?
>>
>> Thanks,
>> Gao Xiang
>>
>> > Also, I will modify the code to record only data extents.
>> >
>> > --Pratik.
>> >
>> > On Sun, Dec 29, 2019 at 8:26 AM Gao Xiang <hsiangkao at aol.com> wrote:
>> >
>> > > Hi Pratik,
>> > >
>> > > On Fri, Dec 27, 2019 at 09:13:48PM +0530, Pratik Shinde wrote:
>> > > > since this patch is quite different from previous patches I am
>> treating
>> > > > this as new patch.
>> > > >
>> > > > 1) On disk extent format for erofs data blocks.
>> > > > 2) Detect holes inside files & skip allocation for hole blocks.
>> > > >
>> > > > Signed-off-by: Pratik Shinde <pratikshinde320 at gmail.com>
>> > > > ---
>> > > > include/erofs/internal.h | 21 ++++++-
>> > > > lib/inode.c | 155
>> > > +++++++++++++++++++++++++++++++++++++++++------
>> > > > 2 files changed, 156 insertions(+), 20 deletions(-)
>> > > >
>> > > > diff --git a/include/erofs/internal.h b/include/erofs/internal.h
>> > > > index e13adda..128aa63 100644
>> > > > --- a/include/erofs/internal.h
>> > > > +++ b/include/erofs/internal.h
>> > > > @@ -63,7 +63,7 @@ struct erofs_sb_info {
>> > > > extern struct erofs_sb_info sbi;
>> > > >
>> > > > struct erofs_inode {
>> > > > - struct list_head i_hash, i_subdirs, i_xattrs;
>> > > > + struct list_head i_hash, i_subdirs, i_xattrs, i_extents;
>> > > >
>> > > > unsigned int i_count;
>> > > > struct erofs_inode *i_parent;
>> > > > @@ -93,6 +93,7 @@ struct erofs_inode {
>> > > >
>> > > > unsigned int xattr_isize;
>> > > > unsigned int extent_isize;
>> > > > + unsigned int extent_meta_isize;
>> > >
>> > > maybe sparse_extent_isize is better...
>> > >
>> > > p.s. maybe we could send another patch rename extent_isize to
>> > > compress_extent_isize or some better name...
>> > >
>> > > >
>> > > > erofs_nid_t nid;
>> > > > struct erofs_buffer_head *bh;
>> > > > @@ -139,5 +140,23 @@ static inline const char *erofs_strerror(int
>> err)
>> > > > return msg;
>> > > > }
>> > > >
>> > > > +#define HOLE_BLK -1
>> > > > +/* on disk extent format */
>> > > > +struct erofs_extent {
>> > > > + __le32 ee_lblk;
>> > > > + __le32 ee_pblk;
>> > > > + __le32 ee_len;
>> > > > +};
>> > > > +
>> > > > +struct erofs_extent_node {
>> > > > + struct list_head next;
>> > > > + erofs_blk_t lblk;
>> > > > + erofs_blk_t pblk;
>> > > > + u32 len;
>> > > > +};
>> > > > +
>> > > > +struct erofs_inline_extent_header {
>> > > > + u32 count;
>> > > > +};
>> > > > #endif
>> > > >
>> > > > diff --git a/lib/inode.c b/lib/inode.c
>> > > > index 0e19b11..a6af509 100644
>> > > > --- a/lib/inode.c
>> > > > +++ b/lib/inode.c
>> > > > @@ -38,6 +38,99 @@ static unsigned char erofs_type_by_mode[S_IFMT >>
>> > > S_SHIFT] = {
>> > > >
>> > > > struct list_head inode_hashtable[NR_INODE_HASHTABLE];
>> > > >
>> > > > +
>> > > > +#define IS_HOLE(start, end) (roundup(start, EROFS_BLKSIZ) == start
>> &&
>> > > \
>> > > > + roundup(end, EROFS_BLKSIZ) == end &&
>> \
>> > > > + (end - start) % EROFS_BLKSIZ == 0)
>> > >
>> > > See below..
>> > >
>> > > > +
>> > > > +/* returns the number of holes present in the file */
>> > > > +unsigned int erofs_read_extents(struct erofs_inode *inode,
>> > > > + struct list_head *extents)
>> > > > +{
>> > > > + int fd, st, en, dt;
>> > > > + unsigned int nholes = 0;
>> > > > + erofs_off_t data, hole, len, last_data;
>> > > > + struct erofs_extent_node *e_hole, *e_data;
>> > > > +
>> > > > + fd = open(inode->i_srcpath, O_RDONLY);
>> > > > + if (fd < 0) {
>> > > > + return -errno;
>> > > > + }
>> > > > + len = lseek(fd, 0, SEEK_END);
>> > > > + if (lseek(fd, 0, SEEK_SET) == -1)
>> > > > + return -errno;
>> > > > + data = 0;
>> > > > + last_data = 0;
>> > > > + while (data < len) {
>> > > > + hole = lseek(fd, data, SEEK_HOLE);
>> > > > + if (hole == len)
>> > > > + break;
>> > > > + data = lseek(fd, hole, SEEK_DATA);
>> > > > + if (data < 0 || hole > data) {
>> > > > + return -EINVAL;
>> > > > + }
>> > > > + if (IS_HOLE(hole, data)) {
>> > > > + st = hole >> S_SHIFT;
>> > > > + en = data >> S_SHIFT;
>> > > > + dt = last_data >> S_SHIFT;
>> > >
>> > > Why using S_SHIFT here, some special meaning?
>> > >
>> > > > + last_data = data;
>> > > > + e_data = malloc(sizeof(struct
>> erofs_extent_node));
>> > > > + if (e_data == NULL)
>> > > > + return -ENOMEM;
>> > > > + e_data->lblk = dt;
>> > > > + e_data->len = (st - dt);
>> > > > + list_add_tail(&e_data->next, extents);
>> > > > + e_hole = malloc(sizeof(struct
>> erofs_extent_node));
>> > > > + if (e_hole == NULL)
>> > > > + return -ENOMEM;
>> > > > + e_hole->lblk = st;
>> > > > + e_hole->pblk = HOLE_BLK;
>> > > > + e_hole->len = (en - st);
>> > > > + list_add_tail(&e_hole->next, extents);
>> > > > + nholes += e_hole->len;
>> > >
>> > > Maybe we don't need to emit all HOLK extents since all data extents
>> > > are with _length_... It is easy to detect all holes between extents...
>> > >
>> > > If some block doesn't belong to any extent, it's a hole.
>> > >
>> > > Thanks,
>> > > Gao Xiang
>> > >
>> > > > + }
>> > > > + }
>> > > > + /* rounddown to exclude tail-end data */
>> > > > + if (last_data < len && (len - last_data) >= EROFS_BLKSIZ) {
>> > > > + e_data = malloc(sizeof(struct erofs_extent_node));
>> > > > + if (e_data == NULL)
>> > > > + return -ENOMEM;
>> > > > + st = last_data >> S_SHIFT;
>> > > > + e_data->lblk = st;
>> > > > + e_data->len = rounddown((len - last_data),
>> EROFS_BLKSIZ)
>> > > >> S_SHIFT;
>> > > > + list_add_tail(&e_data->next, extents);
>> > > > + }
>> > > > + return nholes;
>> > > > +}
>> > > > +
>> > > > +char *erofs_create_extent_buffer(struct list_head *extents,
>> unsigned
>> > > int size)
>> > > > +{
>> > > > + struct erofs_extent_node *e_node;
>> > > > + struct erofs_inline_extent_header *header;
>> > > > + char *buf;
>> > > > + unsigned int p = 0;
>> > > > +
>> > > > + buf = malloc(size);
>> > > > + if (buf == NULL)
>> > > > + return ERR_PTR(-ENOMEM);
>> > > > + header = (struct erofs_inline_extent_header *) buf;
>> > > > + header->count = 0;
>> > > > + p += sizeof(struct erofs_inline_extent_header);
>> > > > + list_for_each_entry(e_node, extents, next) {
>> > > > + const struct erofs_extent ee = {
>> > > > + .ee_lblk = cpu_to_le32(e_node->lblk),
>> > > > + .ee_pblk = cpu_to_le32(e_node->pblk),
>> > > > + .ee_len = cpu_to_le32(e_node->len)
>> > > > + };
>> > > > + memcpy(buf + p, &ee, sizeof(struct erofs_extent));
>> > > > + p += sizeof(struct erofs_extent);
>> > > > + header->count++;
>> > > > + list_del(&e_node->next);
>> > > > + free(e_node);
>> > > > + }
>> > > > + return buf;
>> > > > +}
>> > > > +
>> > > > void erofs_inode_manager_init(void)
>> > > > {
>> > > > unsigned int i;
>> > > > @@ -304,8 +397,9 @@ static bool erofs_file_is_compressible(struct
>> > > erofs_inode *inode)
>> > > >
>> > > > int erofs_write_file(struct erofs_inode *inode)
>> > > > {
>> > > > - unsigned int nblocks, i;
>> > > > + unsigned int nblocks, i, j, nholes;
>> > > > int ret, fd;
>> > > > + struct erofs_extent_node *e_node;
>> > > >
>> > > > if (!inode->i_size) {
>> > > > inode->datalayout = EROFS_INODE_FLAT_PLAIN;
>> > > > @@ -322,31 +416,43 @@ int erofs_write_file(struct erofs_inode
>> *inode)
>> > > > /* fallback to all data uncompressed */
>> > > > inode->datalayout = EROFS_INODE_FLAT_INLINE;
>> > > > nblocks = inode->i_size / EROFS_BLKSIZ;
>> > > > -
>> > > > - ret = __allocate_inode_bh_data(inode, nblocks);
>> > > > + nholes = erofs_read_extents(inode, &inode->i_extents);
>> > > > + if (nholes < 0)
>> > > > + return nholes;
>> > > > + if (nblocks < 0)
>> > > > + return nblocks;
>> > > > + ret = __allocate_inode_bh_data(inode, nblocks - nholes);
>> > > > if (ret)
>> > > > return ret;
>> > > >
>> > > > fd = open(inode->i_srcpath, O_RDONLY | O_BINARY);
>> > > > if (fd < 0)
>> > > > return -errno;
>> > > > -
>> > > > - for (i = 0; i < nblocks; ++i) {
>> > > > - char buf[EROFS_BLKSIZ];
>> > > > -
>> > > > - ret = read(fd, buf, EROFS_BLKSIZ);
>> > > > - if (ret != EROFS_BLKSIZ) {
>> > > > - if (ret < 0)
>> > > > - goto fail;
>> > > > - close(fd);
>> > > > - return -EAGAIN;
>> > > > + i = inode->u.i_blkaddr;
>> > > > + inode->extent_meta_isize = sizeof(struct
>> > > erofs_inline_extent_header);
>> > > > + list_for_each_entry(e_node, &inode->i_extents, next) {
>> > > > + inode->extent_meta_isize += sizeof(struct
>> erofs_extent);
>> > > > + if (e_node->pblk == HOLE_BLK) {
>> > > > + lseek(fd, e_node->len * EROFS_BLKSIZ,
>> SEEK_CUR);
>> > > > + continue;
>> > > > }
>> > > > + e_node->pblk = i;
>> > > > + i += e_node->len;
>> > > > + for (j = 0; j < e_node->len; j++) {
>> > > > + char buf[EROFS_BLKSIZ];
>> > > > + ret = read(fd, buf, EROFS_BLKSIZ);
>> > > > + if (ret != EROFS_BLKSIZ) {
>> > > > + if (ret < 0)
>> > > > + goto fail;
>> > > > + close(fd);
>> > > > + return -EAGAIN;
>> > > > + }
>> > > > + ret = blk_write(buf, e_node->pblk + j, 1);
>> > > > + if (ret)
>> > > > + goto fail;
>> > > >
>> > > > - ret = blk_write(buf, inode->u.i_blkaddr + i, 1);
>> > > > - if (ret)
>> > > > - goto fail;
>> > > > + }
>> > > > }
>> > > > -
>> > > > /* read the tail-end data */
>> > > > inode->idata_size = inode->i_size % EROFS_BLKSIZ;
>> > > > if (inode->idata_size) {
>> > > > @@ -479,8 +585,19 @@ static bool erofs_bh_flush_write_inode(struct
>> > > erofs_buffer_head *bh)
>> > > > if (ret)
>> > > > return false;
>> > > > free(inode->compressmeta);
>> > > > + off += inode->extent_isize;
>> > > > }
>> > > >
>> > > > + if (inode->extent_meta_isize) {
>> > > > + char *extents =
>> > > erofs_create_extent_buffer(&inode->i_extents,
>> > > > +
>> > > inode->extent_meta_isize);
>> > > > + if (IS_ERR(extents))
>> > > > + return false;
>> > > > + ret = dev_write(extents, off,
>> inode->extent_meta_isize);
>> > > > + free(extents);
>> > > > + if (ret)
>> > > > + return false;
>> > > > + }
>> > > > inode->bh = NULL;
>> > > > erofs_iput(inode);
>> > > > return erofs_bh_flush_generic_end(bh);
>> > > > @@ -737,10 +854,11 @@ struct erofs_inode *erofs_new_inode(void)
>> > > >
>> > > > init_list_head(&inode->i_subdirs);
>> > > > init_list_head(&inode->i_xattrs);
>> > > > + init_list_head(&inode->i_extents);
>> > > >
>> > > > inode->idata_size = 0;
>> > > > inode->xattr_isize = 0;
>> > > > - inode->extent_isize = 0;
>> > > > + inode->extent_meta_isize = 0;
>> > > >
>> > > > inode->bh = inode->bh_inline = inode->bh_data = NULL;
>> > > > inode->idata = NULL;
>> > > > @@ -961,4 +1079,3 @@ struct erofs_inode
>> > > *erofs_mkfs_build_tree_from_path(struct erofs_inode *parent,
>> > > >
>> > > > return erofs_mkfs_build_tree(inode);
>> > > > }
>> > > > -
>> > > > --
>> > > > 2.9.3
>> > > >
>> > >
>>
>
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