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Date: Wed, 4 Dec 2013 11:47:58 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: "Darrick J. Wong" <darrick.wong@...cle.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 07:02:42PM -0800, Darrick J. Wong wrote:
[...]
> > +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.
Good catch! I will fix it soon.
Thanks,
- Zheng
>
> > + 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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