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Date: Tue, 3 Dec 2013 19:02:42 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: Zheng Liu <gnehzuil.liu@...il.com>
Cc: linux-ext4@...r.kernel.org, "Theodore Ts'o" <tytso@....edu>,
Zheng Liu <wenqing.lz@...bao.com>
Subject: Re: [PATCH v2 17/28] libext2fs: handle inline data in read/write
function
On Tue, Dec 03, 2013 at 08:11:44PM +0800, Zheng Liu wrote:
> From: Zheng Liu <wenqing.lz@...bao.com>
>
> Currently ext2fs_file_read/write are used to copy data from/to a file.
> But they manipulate data by blocksize. For supporting inline data, we
> handle it in two new fucntions called ext2fs_file_read/write_inline_data.
>
> In read path the implementation is straightforward. But in write path
> things get more complicated because if the size of data is greater than
> the maximum size of inline data we will expand this file. So now we
> will check this in ext2fs_xattr_set(). If this inode doesn't have
> enough space, it will return EXT2_ET_INLINE_DATA_NO_SPACE error. Then
> the caller will check this error and tries to expand the file.
>
> The following commands in debugfs can handle inline_data feature after
> applying this patch:
> - dump
> - cat
> - rdump
> - write
>
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
> ---
> debugfs/debugfs.c | 13 ++++--
> lib/ext2fs/ext2_err.et.in | 3 ++
> lib/ext2fs/ext2fsP.h | 6 +++
> lib/ext2fs/ext_attr.c | 76 +++++++++++++++++++++++++++++++
> lib/ext2fs/fileio.c | 108 +++++++++++++++++++++++++++++++++++++++++++++
> lib/ext2fs/inline_data.c | 90 ++++++++++++++++++++++++++++++++++---
> 6 files changed, 287 insertions(+), 9 deletions(-)
>
> diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
> index d1c81f1..0903c8e 100644
> --- a/debugfs/debugfs.c
> +++ b/debugfs/debugfs.c
> @@ -1684,7 +1684,6 @@ fail:
> return retval;
> }
>
> -
> void do_write(int argc, char *argv[])
> {
> int fd;
> @@ -1750,8 +1749,11 @@ void do_write(int argc, char *argv[])
> current_fs->now ? current_fs->now : time(0);
> inode.i_links_count = 1;
> inode.i_size = statbuf.st_size;
> - if (current_fs->super->s_feature_incompat &
> - EXT3_FEATURE_INCOMPAT_EXTENTS) {
> + if (EXT2_HAS_INCOMPAT_FEATURE(current_fs->super,
> + EXT4_FEATURE_INCOMPAT_INLINE_DATA)) {
> + inode.i_flags |= EXT4_INLINE_DATA_FL;
> + } else if (current_fs->super->s_feature_incompat &
> + EXT3_FEATURE_INCOMPAT_EXTENTS) {
> int i;
> struct ext3_extent_header *eh;
>
> @@ -1768,6 +1770,11 @@ void do_write(int argc, char *argv[])
> close(fd);
> return;
> }
> + if (inode.i_flags & EXT4_INLINE_DATA_FL) {
> + retval = ext2fs_inline_data_init(current_fs, newfile);
> + if (retval)
> + return;
> + }
> if (LINUX_S_ISREG(inode.i_mode)) {
> if (statbuf.st_blocks < statbuf.st_size / S_BLKSIZE) {
> make_holes = 1;
> diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
> index 0781145..68aa3e0 100644
> --- a/lib/ext2fs/ext2_err.et.in
> +++ b/lib/ext2fs/ext2_err.et.in
> @@ -503,4 +503,7 @@ ec EXT2_ET_EA_NO_SPACE,
> ec EXT2_ET_NO_INLINE_DATA,
> "Inode doesn't have inline data"
>
> +ec EXT2_ET_INLINE_DATA_NO_SPACE,
> + "No free space in inline data"
> +
> end
> diff --git a/lib/ext2fs/ext2fsP.h b/lib/ext2fs/ext2fsP.h
> index bfc321c..e159128 100644
> --- a/lib/ext2fs/ext2fsP.h
> +++ b/lib/ext2fs/ext2fsP.h
> @@ -102,6 +102,12 @@ extern errcode_t ext2fs_inline_data_dir_iterate(ext2_filsys fs,
> int ref_offset,
> void *priv_data),
> void *priv_data);
> +extern errcode_t ext2fs_inline_data_get(ext2_filsys fs, ext2_ino_t ino,
> + struct ext2_inode *inode,
> + void *buf, size_t *size);
> +extern errcode_t ext2fs_inline_data_set(ext2_filsys fs, ext2_ino_t ino,
> + struct ext2_inode *inode,
> + void *buf, size_t size);
>
> /* Generic numeric progress meter */
>
> diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
> index 0e9a9ab..98f0fbb 100644
> --- a/lib/ext2fs/ext_attr.c
> +++ b/lib/ext2fs/ext_attr.c
> @@ -818,6 +818,71 @@ errcode_t ext2fs_xattr_get(struct ext2_xattr_handle *h, const char *key,
> return EXT2_ET_EA_KEY_NOT_FOUND;
> }
>
> +static errcode_t ext2fs_xattr_max_size(struct ext2_xattr_handle *handle, size_t *size)
> +{
> + struct ext2_ext_attr_header *header;
> + struct ext2_ext_attr_entry *entry;
> + struct ext2_inode_large *inode;
> + __u32 ea_inode_magic;
> + unsigned int storage_size, freesize, minoff;
> + void *start;
> + int i;
> + errcode_t err;
> +
> + i = EXT2_INODE_SIZE(handle->fs->super);
> + if (i < sizeof(*inode))
> + i = sizeof(*inode);
> + err = ext2fs_get_memzero(i, &inode);
> + if (err)
> + return err;
> +
> + err = ext2fs_read_inode_full(handle->fs, handle->ino,
> + (struct ext2_inode *)inode,
> + EXT2_INODE_SIZE(handle->fs->super));
> + if (err)
> + goto out;
> +
> + /* Does the inode have size for EA? */
> + if (EXT2_INODE_SIZE(handle->fs->super) <= EXT2_GOOD_OLD_INODE_SIZE +
> + inode->i_extra_isize +
> + sizeof(__u32)) {
> + err = EXT2_ET_INLINE_DATA_NO_SPACE;
> + goto out;
> + }
> +
> + minoff = EXT2_INODE_SIZE(handle->fs->super) -
> + sizeof(*inode) - sizeof(__u32);
> + memcpy(&ea_inode_magic, ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> + inode->i_extra_isize, sizeof(__u32));
> + if (ea_inode_magic == EXT2_EXT_ATTR_MAGIC) {
> + /* has xattrs. calculate the size */
> + storage_size = EXT2_INODE_SIZE(handle->fs->super) -
> + EXT2_GOOD_OLD_INODE_SIZE - inode->i_extra_isize -
> + sizeof(__u32);
> + start= ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
> + inode->i_extra_isize + sizeof(__u32);
> + entry = start;
> + while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
> + if (!entry->e_value_block && entry->e_value_size) {
> + unsigned int offs = entry->e_value_offs;
> + if (offs < minoff)
> + minoff = offs;
> + }
> + entry = EXT2_EXT_ATTR_NEXT(entry);
> + }
> + *size = minoff - ((char *)entry - (char *)start) - sizeof(__u32);
> + } else {
> + /* no xattr. return a maximum size */
> + *size = EXT2_EXT_ATTR_SIZE(minoff -
> + EXT2_EXT_ATTR_LEN(strlen("data")) -
> + EXT2_EXT_ATTR_ROUND - sizeof(__u32));
> + }
> +
> +out:
> + ext2fs_free_mem(&inode);
> + return err;
> +}
> +
> errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
> const char *key,
> const void *value,
> @@ -827,6 +892,17 @@ errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
> char *new_value;
> errcode_t err;
>
> + /* we need to check inline data space */
> + if (strcmp(key, "system.data") == 0) {
> + size_t max_size;
> +
> + err = ext2fs_xattr_max_size(handle, &max_size);
> + if (err)
> + return err;
> + if (value_len > max_size)
> + return EXT2_ET_INLINE_DATA_NO_SPACE;
> + }
> +
> last_empty = NULL;
> for (x = handle->attrs; x < handle->attrs + handle->length; x++) {
> if (!x->name) {
> diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
> index 02e6263..acb705d 100644
> --- a/lib/ext2fs/fileio.c
> +++ b/lib/ext2fs/fileio.c
> @@ -224,6 +224,39 @@ errcode_t ext2fs_file_close(ext2_file_t file)
> }
>
>
> +static errcode_t
> +ext2fs_file_read_inline_data(ext2_file_t file, void *buf,
> + unsigned int wanted, unsigned int *got)
> +{
> + ext2_filsys fs;
> + errcode_t retval;
> + unsigned int start, count = 0;
> + size_t size;
> +
> + fs = file->fs;
> + retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
> + file->buf, &size);
> + if (retval)
> + return retval;
> +
> + if (file->pos >= size)
> + goto out;
> +
> + start = file->pos % size;
If file->pos can never be larger than size, this is unnecessary.
> + count = size - start;
> + if (count > wanted)
> + count = wanted;
> + memcpy(buf, file->buf + start, count);
> + file->pos += count;
> + buf += count;
> +
> +out:
> + if (got)
> + *got = count;
> + return retval;
> +}
> +
> +
> errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
> unsigned int wanted, unsigned int *got)
> {
> @@ -236,6 +269,10 @@ errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
> EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
> fs = file->fs;
>
> + /* If an inode has inline data, things get complicated. */
> + if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
> + return ext2fs_file_read_inline_data(file, buf, wanted, got);
> +
> while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
> retval = sync_buffer_position(file);
> if (retval)
> @@ -266,6 +303,67 @@ fail:
> }
>
>
> +static errcode_t
> +ext2fs_file_write_inline_data(ext2_file_t file, const void *buf,
> + unsigned int nbytes, unsigned int *written)
> +{
> + ext2_filsys fs;
> + errcode_t retval;
> + unsigned int start, count = 0;
> + size_t size;
> +
> + fs = file->fs;
> + retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
> + file->buf, &size);
> + if (retval)
> + return retval;
> +
> + if (file->pos < size) {
> + start = file->pos % fs->blocksize;
Since we're not dealing with blocks, I don't think you need to '%' with the
block size.
--D
> + count = nbytes - start;
> + memcpy(file->buf + start, buf, count);
> +
> + retval = ext2fs_inline_data_set(fs, file->ino, &file->inode,
> + file->buf, count);
> + if (retval == EXT2_ET_INLINE_DATA_NO_SPACE)
> + goto expand;
> + if (retval)
> + return retval;
> +
> + file->pos += count;
> +
> + /* Update inode size */
> + if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
> + errcode_t rc;
> +
> + rc = ext2fs_file_set_size2(file, file->pos);
> + if (retval == 0)
> + retval = rc;
> + }
> +
> + if (written)
> + *written = count;
> + return 0;
> + }
> +
> +expand:
> + retval = ext2fs_inline_data_expand(fs, file->ino);
> + if (retval)
> + return retval;
> + /*
> + * reload inode and return no space error
> + *
> + * XXX: file->inode could be copied from the outside
> + * in ext2fs_file_open2(). We have no way to modify
> + * the outside inode.
> + */
> + retval = ext2fs_read_inode(fs, file->ino, &file->inode);
> + if (retval)
> + return retval;
> + return EXT2_ET_INLINE_DATA_NO_SPACE;
> +}
> +
> +
> errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
> unsigned int nbytes, unsigned int *written)
> {
> @@ -280,6 +378,16 @@ errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
> if (!(file->flags & EXT2_FILE_WRITE))
> return EXT2_ET_FILE_RO;
>
> + /* If an inode has inline data, things get complicated. */
> + if (file->inode.i_flags & EXT4_INLINE_DATA_FL) {
> + retval = ext2fs_file_write_inline_data(file, buf, nbytes,
> + written);
> + if (retval != EXT2_ET_INLINE_DATA_NO_SPACE)
> + return retval;
> + /* fall through to read data from the block */
> + retval = 0;
> + }
> +
> while (nbytes > 0) {
> retval = sync_buffer_position(file);
> if (retval)
> diff --git a/lib/ext2fs/inline_data.c b/lib/ext2fs/inline_data.c
> index 16af814..4a35209 100644
> --- a/lib/ext2fs/inline_data.c
> +++ b/lib/ext2fs/inline_data.c
> @@ -309,6 +309,7 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
> struct ext2_inline_data data;
> errcode_t retval;
> blk64_t blk;
> + size_t inline_size;
> char *inline_buf = 0;
> char *blk_buf = 0;
>
> @@ -327,8 +328,8 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
> retval = ext2fs_inline_data_ea_get(&data);
> if (retval)
> return retval;
> - retval = ext2fs_get_mem(EXT4_MIN_INLINE_DATA_SIZE + data.ea_size,
> - &inline_buf);
> + inline_size = data.ea_size + EXT4_MIN_INLINE_DATA_SIZE;
> + retval = ext2fs_get_mem(inline_size, &inline_buf);
> if (retval)
> goto errout;
>
> @@ -347,10 +348,14 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
> if (retval)
> goto errout;
>
> - /* Adjust the rec_len */
> - retval = ext2fs_inline_data_convert_dir(fs, ino, blk_buf, inline_buf,
> - EXT4_MIN_INLINE_DATA_SIZE +
> - data.ea_size);
> + if (LINUX_S_ISDIR(inode.i_mode)) {
> + /* Adjust the rec_len */
> + retval = ext2fs_inline_data_convert_dir(fs, ino, blk_buf,
> + inline_buf, inline_size);
> + } else {
> + /* Copy data for a regular inode */
> + memcpy(blk_buf, inline_buf, inline_size);
> + }
> if (retval)
> goto errout;
>
> @@ -389,3 +394,76 @@ errout:
> ext2fs_free_mem(&data.ea_data);
> return retval;
> }
> +
> +/*
> + * When caller uses this function to retrieve the inline data, it must
> + * allocate a buffer which has the size of inline data. The size of
> + * inline data can be know by ext2fs_inline_data_get_size().
> + */
> +errcode_t ext2fs_inline_data_get(ext2_filsys fs, ext2_ino_t ino,
> + struct ext2_inode *inode,
> + void *buf, size_t *size)
> +{
> + struct ext2_inode inode_buf;
> + struct ext2_inline_data data;
> + errcode_t retval;
> +
> + if (!inode) {
> + retval = ext2fs_read_inode(fs, ino, &inode_buf);
> + if (retval)
> + return retval;
> + inode = &inode_buf;
> + }
> +
> + data.fs = fs;
> + data.ino = ino;
> + retval = ext2fs_inline_data_ea_get(&data);
> + if (retval)
> + return retval;
> +
> + memcpy(buf, (void *)inode->i_block, EXT4_MIN_INLINE_DATA_SIZE);
> + if (data.ea_size > 0)
> + memcpy(buf + EXT4_MIN_INLINE_DATA_SIZE,
> + data.ea_data, data.ea_size);
> +
> + if (size)
> + *size = EXT4_MIN_INLINE_DATA_SIZE + data.ea_size;
> + ext2fs_free_mem(&data.ea_data);
> + return 0;
> +}
> +
> +errcode_t ext2fs_inline_data_set(ext2_filsys fs, ext2_ino_t ino,
> + struct ext2_inode *inode,
> + void *buf, size_t size)
> +{
> + struct ext2_inode inode_buf;
> + struct ext2_inline_data data;
> + unsigned int max_size = 0;
> + errcode_t retval;
> +
> + if (!inode) {
> + retval = ext2fs_read_inode(fs, ino, &inode_buf);
> + if (retval)
> + return retval;
> + inode = &inode_buf;
> + }
> +
> + /* simple case */
> + if (size <= EXT4_MIN_INLINE_DATA_SIZE) {
> + memcpy((void *)inode->i_block, buf, size);
> + return ext2fs_write_inode(fs, ino, inode);
> + }
> +
> + /*
> + * complicated case
> + */
> + memcpy((void *)inode->i_block, buf, EXT4_MIN_INLINE_DATA_SIZE);
> + retval = ext2fs_write_inode(fs, ino, inode);
> + if (retval)
> + return retval;
> + data.fs = fs;
> + data.ino = ino;
> + data.ea_size = size - EXT4_MIN_INLINE_DATA_SIZE;
> + data.ea_data = buf + EXT4_MIN_INLINE_DATA_SIZE;
> + return ext2fs_inline_data_ea_set(&data);
> +}
> --
> 1.7.9.7
>
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