On 10/26/10 12:54 PM, Lukas Czerner wrote:
> In order to provide generic "discard" function for all e2fsprogs tools
> add a discard function prototype into struct_io_manager. Specific
> function for specific io managers can be crated that way.
>
> This commit also creates unix_discard function which uses BLKDISCARD
> ioctl to discard data blocks on the block device and bind it into
> unit_io_manager structure to be available for all e2fsprogs tools.
> Note that BLKDISCARD is still Linux specific ioctl, however other
> unix systems may provide similar functionality. So far the
> unix_discard() remains linux specific hence is embedded in #ifdef
> __linux__ macro.
>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> ---
> lib/ext2fs/ext2_io.h | 2 ++
> lib/ext2fs/unix_io.c | 41 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 43 insertions(+), 0 deletions(-)
>
> diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
> index ccc9c8b..d202007 100644
> --- a/lib/ext2fs/ext2_io.h
> +++ b/lib/ext2fs/ext2_io.h
> @@ -83,6 +83,8 @@ struct struct_io_manager {
> int count, void *data);
> errcode_t (*write_blk64)(io_channel channel, unsigned long long block,
> int count, const void *data);
> + errcode_t (*discard)(io_channel channel, unsigned long long block,
> + unsigned long long count, const void *data);
> long reserved[16];
> };
>
> diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
> index 1df1fdd..5b6cdec 100644
> --- a/lib/ext2fs/unix_io.c
> +++ b/lib/ext2fs/unix_io.c
> @@ -115,6 +115,8 @@ static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
> int count, void *data);
> static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
> int count, const void *data);
> +static errcode_t unix_discard(io_channel channel, unsigned long long block,
> + unsigned long long count, const void *data);
>
> static struct struct_io_manager struct_unix_manager = {
> EXT2_ET_MAGIC_IO_MANAGER,
> @@ -130,6 +132,7 @@ static struct struct_io_manager struct_unix_manager = {
> unix_get_stats,
> unix_read_blk64,
> unix_write_blk64,
> + unix_discard,
> };
>
> io_manager unix_io_manager = &struct_unix_manager;
> @@ -834,3 +837,41 @@ static errcode_t unix_set_option(io_channel channel, const char *option,
> }
> return EXT2_ET_INVALID_ARGUMENT;
> }
> +
> +#ifdef __linux__
> +
> +#ifndef BLKDISCARD
> +#define BLKDISCARD _IO(0x12,119)
> +#endif
> +
> +static errcode_t unix_discard(io_channel channel, unsigned long long block,
> + unsigned long long count, const void *data)
> +{
> +
> + struct struct_ext2_filsys *fs;
> + struct unix_private_data *u_priv;
> + errcode_t retval = 0;
> + __uint64_t range[2];
> + int blocksize;
> +
> + EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
> + u_priv = (struct unix_private_data *) channel->private_data;
> + EXT2_CHECK_MAGIC(u_priv, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
> +
> + fs = (struct struct_ext2_filsys *) data;
> + if (!fs)
> + return EXT2_ET_INVALID_ARGUMENT;
> +
> + blocksize = EXT2_BLOCK_SIZE(fs->super);
This seems a little convoluted; you pass in *data, which gets you the fs,
from which you get the super, from which you get the blocksize,
which is all that you ever actually use here:
> + range[0] = (__uint64_t)(block);
> + range[1] = (__uint64_t)(count);
> + range[0] *= (__uint64_t)(blocksize);
> + range[1] *= (__uint64_t)(blocksize);
any reason to not just pass in the blocksize?
Maybe this is for flexibility for not-linux, but I guess we don't know what
they need anyway...?
And if you do that you can change "u_priv" to "data" just to match the
other handlers, perhaps.
-Eric
> + return ioctl(u_priv->dev, BLKDISCARD, &range);
> +}
> +
> +#else
> +#define unix_discard(channel, block, count) EXT2_ET_UNIMPLEMENTED
> +#endif
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