[PATCH 1/2] Squashfs: add LZ4 compression support
Add support for reading file systems compressed with the
LZ4 compression algorithm.
This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: Phillip Lougher
---
fs/squashfs/lz4_wrapper.c | 142 +
fs/squashfs/squashfs_fs.h |1 +
2 files changed, 143 insertions(+)
create mode 100644 fs/squashfs/lz4_wrapper.c
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644
index 000..c31e2bc
--- /dev/null
+++ b/fs/squashfs/lz4_wrapper.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2013, 2014
+ * Phillip Lougher
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include
+#include
+#include
+#include
+#include
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs.h"
+#include "decompressor.h"
+#include "page_actor.h"
+
+#define LZ4_LEGACY 1
+
+struct lz4_comp_opts {
+ __le32 version;
+ __le32 flags;
+};
+
+struct squashfs_lz4 {
+ void *input;
+ void *output;
+};
+
+
+static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
+ void *buff, int len)
+{
+ struct lz4_comp_opts *comp_opts = buff;
+
+ /* LZ4 compressed filesystems always have compression options */
+ if (comp_opts == NULL || len < sizeof(*comp_opts))
+ return ERR_PTR(-EIO);
+
+ if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
+ /* LZ4 format currently used by the kernel is the 'legacy'
+* format */
+ ERROR("Unknown LZ4 version\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ return NULL;
+}
+
+
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
+{
+ int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
+ struct squashfs_lz4 *stream;
+
+ stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+ if (stream == NULL)
+ goto failed;
+ stream->input = vmalloc(block_size);
+ if (stream->input == NULL)
+ goto failed2;
+ stream->output = vmalloc(block_size);
+ if (stream->output == NULL)
+ goto failed3;
+
+ return stream;
+
+failed3:
+ vfree(stream->input);
+failed2:
+ kfree(stream);
+failed:
+ ERROR("Failed to initialise LZ4 decompressor\n");
+ return ERR_PTR(-ENOMEM);
+}
+
+
+static void lz4_free(void *strm)
+{
+ struct squashfs_lz4 *stream = strm;
+
+ if (stream) {
+ vfree(stream->input);
+ vfree(stream->output);
+ }
+ kfree(stream);
+}
+
+
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
+ struct buffer_head **bh, int b, int offset, int length,
+ struct squashfs_page_actor *output)
+{
+ struct squashfs_lz4 *stream = strm;
+ void *buff = stream->input, *data;
+ int avail, i, bytes = length, res;
+ size_t dest_len = output->length;
+
+ for (i = 0; i < b; i++) {
+ avail = min(bytes, msblk->devblksize - offset);
+ memcpy(buff, bh[i]->b_data + offset, avail);
+ buff += avail;
+ bytes -= avail;
+ offset = 0;
+ put_bh(bh[i]);
+ }
+
+ res = lz4_decompress_unknownoutputsize(stream->input, length,
+ stream->output, _len);
+ if (res)
+ return -EIO;
+
+ bytes = dest_len;
+ data = squashfs_first_page(output);
+ buff = stream->output;
+ while (data) {
+ if (bytes <= PAGE_CACHE_SIZE) {
+ memcpy(data, buff, bytes);
+ break;
+ }
+ memcpy(data, buff, PAGE_CACHE_SIZE);
+ buff += PAGE_CACHE_SIZE;
+ bytes -= PAGE_CACHE_SIZE;
+ data = squashfs_next_page(output);
+ }
+ squashfs_finish_page(output);
+
+ return dest_len;
+}
+
+const struct squashfs_decompressor squashfs_lz4_comp_ops = {
+ .init = lz4_init,
+ .comp_opts = lz4_comp_opts,
+ .free = lz4_free,
+ .decompress = lz4_uncompress,
+ .id = LZ4_COMPRESSION,
+ .name = "lz4",
+ .supported = 1
+};
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 4b2beda..506f4ba 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -240,6 +240,7 @@ struct meta_index {
#define LZMA_COMPRESSION 2
#define LZO_COMPRESSION3
#define XZ_COMPRESSION 4
+#define LZ4_COMPRESSION5
struct squashfs_super_block {
__le32 s_magic;
--
1.7.10.4
--
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/2] Squashfs: add LZ4 compression support
Add support for reading file systems compressed with the
LZ4 compression algorithm.
This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: Phillip Lougher phil...@squashfs.org.uk
---
fs/squashfs/lz4_wrapper.c | 142 +
fs/squashfs/squashfs_fs.h |1 +
2 files changed, 143 insertions(+)
create mode 100644 fs/squashfs/lz4_wrapper.c
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644
index 000..c31e2bc
--- /dev/null
+++ b/fs/squashfs/lz4_wrapper.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2013, 2014
+ * Phillip Lougher phil...@squashfs.org.uk
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include linux/buffer_head.h
+#include linux/mutex.h
+#include linux/slab.h
+#include linux/vmalloc.h
+#include linux/lz4.h
+
+#include squashfs_fs.h
+#include squashfs_fs_sb.h
+#include squashfs.h
+#include decompressor.h
+#include page_actor.h
+
+#define LZ4_LEGACY 1
+
+struct lz4_comp_opts {
+ __le32 version;
+ __le32 flags;
+};
+
+struct squashfs_lz4 {
+ void *input;
+ void *output;
+};
+
+
+static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
+ void *buff, int len)
+{
+ struct lz4_comp_opts *comp_opts = buff;
+
+ /* LZ4 compressed filesystems always have compression options */
+ if (comp_opts == NULL || len sizeof(*comp_opts))
+ return ERR_PTR(-EIO);
+
+ if (le32_to_cpu(comp_opts-version) != LZ4_LEGACY) {
+ /* LZ4 format currently used by the kernel is the 'legacy'
+* format */
+ ERROR(Unknown LZ4 version\n);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return NULL;
+}
+
+
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
+{
+ int block_size = max_t(int, msblk-block_size, SQUASHFS_METADATA_SIZE);
+ struct squashfs_lz4 *stream;
+
+ stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+ if (stream == NULL)
+ goto failed;
+ stream-input = vmalloc(block_size);
+ if (stream-input == NULL)
+ goto failed2;
+ stream-output = vmalloc(block_size);
+ if (stream-output == NULL)
+ goto failed3;
+
+ return stream;
+
+failed3:
+ vfree(stream-input);
+failed2:
+ kfree(stream);
+failed:
+ ERROR(Failed to initialise LZ4 decompressor\n);
+ return ERR_PTR(-ENOMEM);
+}
+
+
+static void lz4_free(void *strm)
+{
+ struct squashfs_lz4 *stream = strm;
+
+ if (stream) {
+ vfree(stream-input);
+ vfree(stream-output);
+ }
+ kfree(stream);
+}
+
+
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
+ struct buffer_head **bh, int b, int offset, int length,
+ struct squashfs_page_actor *output)
+{
+ struct squashfs_lz4 *stream = strm;
+ void *buff = stream-input, *data;
+ int avail, i, bytes = length, res;
+ size_t dest_len = output-length;
+
+ for (i = 0; i b; i++) {
+ avail = min(bytes, msblk-devblksize - offset);
+ memcpy(buff, bh[i]-b_data + offset, avail);
+ buff += avail;
+ bytes -= avail;
+ offset = 0;
+ put_bh(bh[i]);
+ }
+
+ res = lz4_decompress_unknownoutputsize(stream-input, length,
+ stream-output, dest_len);
+ if (res)
+ return -EIO;
+
+ bytes = dest_len;
+ data = squashfs_first_page(output);
+ buff = stream-output;
+ while (data) {
+ if (bytes = PAGE_CACHE_SIZE) {
+ memcpy(data, buff, bytes);
+ break;
+ }
+ memcpy(data, buff, PAGE_CACHE_SIZE);
+ buff += PAGE_CACHE_SIZE;
+ bytes -= PAGE_CACHE_SIZE;
+ data = squashfs_next_page(output);
+ }
+ squashfs_finish_page(output);
+
+ return dest_len;
+}
+
+const struct squashfs_decompressor squashfs_lz4_comp_ops = {
+ .init = lz4_init,
+ .comp_opts = lz4_comp_opts,
+ .free = lz4_free,
+ .decompress = lz4_uncompress,
+ .id = LZ4_COMPRESSION,
+ .name = lz4,
+ .supported = 1
+};
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 4b2beda..506f4ba 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -240,6 +240,7 @@ struct meta_index {
#define LZMA_COMPRESSION 2
#define LZO_COMPRESSION3
#define XZ_COMPRESSION 4
+#define LZ4_COMPRESSION5
struct squashfs_super_block {
__le32 s_magic;
--
1.7.10.4
--
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the body of a message to majord...@vger.kernel.org
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Re: [PATCH 1/2] Squashfs: add LZ4 compression support
On Mon, 2013-07-22 at 03:21 +0100, Phillip Lougher wrote:
> Add support for reading file systems compressed with the
> LZ4 compression algorithm.
Some whitespace trivia and a naming comment.
> diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
[]
> +static void *lz4_init(struct squashfs_sb_info *msblk, void *buff, int len)
[]
> + /* LZ4 compressed filesystems always have compression options */
> + if(comp_opts == NULL || len < sizeof(*comp_opts)) {
space after ifs please.
> + if(le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
> +
> +
> +static void lz4_free(void *strm)
Single blank line between functions
> +static int lz4_uncompress(struct squashfs_sb_info *msblk, void **buffer,
> + struct buffer_head **bh, int b, int offset, int length, int srclength,
> + int pages)
> +{
> + struct squashfs_lz4 *stream = msblk->stream;
> + void *buff = stream->input;
It's not particularly nice to have both buffer and buff
in the same function.
Maybe void *input though char *input would be better.
> + int avail, i, bytes = length, res;
> + size_t dest_len = srclength;
> +
> + mutex_lock(>read_data_mutex);
> +
> + for (i = 0; i < b; i++) {
> + wait_on_buffer(bh[i]);
> + if (!buffer_uptodate(bh[i]))
> + goto block_release;
> +
> + avail = min(bytes, msblk->devblksize - offset);
> + memcpy(buff, bh[i]->b_data + offset, avail);
> + buff += avail;
> + bytes -= avail;
> + offset = 0;
> + put_bh(bh[i]);
> + }
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/2] Squashfs: add LZ4 compression support
Add support for reading file systems compressed with the
LZ4 compression algorithm.
This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: Phillip Lougher
---
fs/squashfs/lz4_wrapper.c | 163 +
fs/squashfs/squashfs_fs.h |1 +
2 files changed, 164 insertions(+)
create mode 100644 fs/squashfs/lz4_wrapper.c
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644
index 000..681ed94
--- /dev/null
+++ b/fs/squashfs/lz4_wrapper.c
@@ -0,0 +1,163 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2013
+ * Phillip Lougher
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * lz4_wrapper.c
+ */
+
+#include
+#include
+#include
+#include
+#include
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs.h"
+#include "decompressor.h"
+
+#define LZ4_LEGACY 1
+
+struct lz4_comp_opts {
+ __le32 version;
+ __le32 flags;
+};
+
+struct squashfs_lz4 {
+ void *input;
+ void *output;
+};
+
+
+
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff, int len)
+{
+ struct lz4_comp_opts *comp_opts = buff;
+ int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
+ struct squashfs_lz4 *stream;
+ int err = -ENOMEM;
+
+ /* LZ4 compressed filesystems always have compression options */
+ if(comp_opts == NULL || len < sizeof(*comp_opts)) {
+ err = -EIO;
+ goto failed;
+ }
+ if(le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
+ /* LZ4 format currently used by the kernel is the 'legacy'
+* format */
+ ERROR("Unknown LZ4 version\n");
+ err = -EINVAL;
+ goto failed;
+ }
+
+ stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+ if (stream == NULL)
+ goto failed;
+ stream->input = vmalloc(block_size);
+ if (stream->input == NULL)
+ goto failed2;
+ stream->output = vmalloc(block_size);
+ if (stream->output == NULL)
+ goto failed3;
+
+ return stream;
+
+failed3:
+ vfree(stream->input);
+failed2:
+ kfree(stream);
+failed:
+ ERROR("Failed to initialise LZ4 decompressor\n");
+ return ERR_PTR(err);
+}
+
+
+static void lz4_free(void *strm)
+{
+ struct squashfs_lz4 *stream = strm;
+
+ if (stream) {
+ vfree(stream->input);
+ vfree(stream->output);
+ }
+ kfree(stream);
+}
+
+
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void **buffer,
+ struct buffer_head **bh, int b, int offset, int length, int srclength,
+ int pages)
+{
+ struct squashfs_lz4 *stream = msblk->stream;
+ void *buff = stream->input;
+ int avail, i, bytes = length, res;
+ size_t dest_len = srclength;
+
+ mutex_lock(>read_data_mutex);
+
+ for (i = 0; i < b; i++) {
+ wait_on_buffer(bh[i]);
+ if (!buffer_uptodate(bh[i]))
+ goto block_release;
+
+ avail = min(bytes, msblk->devblksize - offset);
+ memcpy(buff, bh[i]->b_data + offset, avail);
+ buff += avail;
+ bytes -= avail;
+ offset = 0;
+ put_bh(bh[i]);
+ }
+
+ res = lz4_decompress_unknownoutputsize(stream->input, length,
+ stream->output, _len);
+ if (res)
+ goto failed;
+
+ bytes = dest_len;
+ for (i = 0, buff = stream->output; bytes && i < pages; i++) {
+ avail = min_t(int, bytes, PAGE_CACHE_SIZE);
+ memcpy(buffer[i], buff, avail);
+ buff += avail;
+ bytes -= avail;
+ }
+ if (bytes)
+ goto failed;
+
+ mutex_unlock(>read_data_mutex);
+ return dest_len;
+
+block_release:
+ for (; i < b; i++)
+ put_bh(bh[i]);
+
+failed:
+ mutex_unlock(>read_data_mutex);
+
+ ERROR("lz4 decompression failed, data probably corrupt\n");
+ return -EIO;
+}
+
+const struct squashfs_decompressor squashfs_lz4_comp_ops = {
+ .init = lz4_init,
+ .free = lz4_free,
+
[PATCH 1/2] Squashfs: add LZ4 compression support
Add support for reading file systems compressed with the
LZ4 compression algorithm.
This patch adds the LZ4 decompressor wrapper code.
Signed-off-by: Phillip Lougher phil...@squashfs.org.uk
---
fs/squashfs/lz4_wrapper.c | 163 +
fs/squashfs/squashfs_fs.h |1 +
2 files changed, 164 insertions(+)
create mode 100644 fs/squashfs/lz4_wrapper.c
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644
index 000..681ed94
--- /dev/null
+++ b/fs/squashfs/lz4_wrapper.c
@@ -0,0 +1,163 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2013
+ * Phillip Lougher phil...@squashfs.org.uk
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * lz4_wrapper.c
+ */
+
+#include linux/buffer_head.h
+#include linux/mutex.h
+#include linux/slab.h
+#include linux/vmalloc.h
+#include linux/lz4.h
+
+#include squashfs_fs.h
+#include squashfs_fs_sb.h
+#include squashfs.h
+#include decompressor.h
+
+#define LZ4_LEGACY 1
+
+struct lz4_comp_opts {
+ __le32 version;
+ __le32 flags;
+};
+
+struct squashfs_lz4 {
+ void *input;
+ void *output;
+};
+
+
+
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff, int len)
+{
+ struct lz4_comp_opts *comp_opts = buff;
+ int block_size = max_t(int, msblk-block_size, SQUASHFS_METADATA_SIZE);
+ struct squashfs_lz4 *stream;
+ int err = -ENOMEM;
+
+ /* LZ4 compressed filesystems always have compression options */
+ if(comp_opts == NULL || len sizeof(*comp_opts)) {
+ err = -EIO;
+ goto failed;
+ }
+ if(le32_to_cpu(comp_opts-version) != LZ4_LEGACY) {
+ /* LZ4 format currently used by the kernel is the 'legacy'
+* format */
+ ERROR(Unknown LZ4 version\n);
+ err = -EINVAL;
+ goto failed;
+ }
+
+ stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+ if (stream == NULL)
+ goto failed;
+ stream-input = vmalloc(block_size);
+ if (stream-input == NULL)
+ goto failed2;
+ stream-output = vmalloc(block_size);
+ if (stream-output == NULL)
+ goto failed3;
+
+ return stream;
+
+failed3:
+ vfree(stream-input);
+failed2:
+ kfree(stream);
+failed:
+ ERROR(Failed to initialise LZ4 decompressor\n);
+ return ERR_PTR(err);
+}
+
+
+static void lz4_free(void *strm)
+{
+ struct squashfs_lz4 *stream = strm;
+
+ if (stream) {
+ vfree(stream-input);
+ vfree(stream-output);
+ }
+ kfree(stream);
+}
+
+
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void **buffer,
+ struct buffer_head **bh, int b, int offset, int length, int srclength,
+ int pages)
+{
+ struct squashfs_lz4 *stream = msblk-stream;
+ void *buff = stream-input;
+ int avail, i, bytes = length, res;
+ size_t dest_len = srclength;
+
+ mutex_lock(msblk-read_data_mutex);
+
+ for (i = 0; i b; i++) {
+ wait_on_buffer(bh[i]);
+ if (!buffer_uptodate(bh[i]))
+ goto block_release;
+
+ avail = min(bytes, msblk-devblksize - offset);
+ memcpy(buff, bh[i]-b_data + offset, avail);
+ buff += avail;
+ bytes -= avail;
+ offset = 0;
+ put_bh(bh[i]);
+ }
+
+ res = lz4_decompress_unknownoutputsize(stream-input, length,
+ stream-output, dest_len);
+ if (res)
+ goto failed;
+
+ bytes = dest_len;
+ for (i = 0, buff = stream-output; bytes i pages; i++) {
+ avail = min_t(int, bytes, PAGE_CACHE_SIZE);
+ memcpy(buffer[i], buff, avail);
+ buff += avail;
+ bytes -= avail;
+ }
+ if (bytes)
+ goto failed;
+
+ mutex_unlock(msblk-read_data_mutex);
+ return dest_len;
+
+block_release:
+ for (; i b; i++)
+ put_bh(bh[i]);
+
+failed:
+ mutex_unlock(msblk-read_data_mutex);
+
+ ERROR(lz4 decompression failed, data probably corrupt\n);
+ return -EIO;
+}
+
+const struct
Re: [PATCH 1/2] Squashfs: add LZ4 compression support
On Mon, 2013-07-22 at 03:21 +0100, Phillip Lougher wrote:
Add support for reading file systems compressed with the
LZ4 compression algorithm.
Some whitespace trivia and a naming comment.
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
[]
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff, int len)
[]
+ /* LZ4 compressed filesystems always have compression options */
+ if(comp_opts == NULL || len sizeof(*comp_opts)) {
space after ifs please.
+ if(le32_to_cpu(comp_opts-version) != LZ4_LEGACY) {
+
+
+static void lz4_free(void *strm)
Single blank line between functions
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void **buffer,
+ struct buffer_head **bh, int b, int offset, int length, int srclength,
+ int pages)
+{
+ struct squashfs_lz4 *stream = msblk-stream;
+ void *buff = stream-input;
It's not particularly nice to have both buffer and buff
in the same function.
Maybe void *input though char *input would be better.
+ int avail, i, bytes = length, res;
+ size_t dest_len = srclength;
+
+ mutex_lock(msblk-read_data_mutex);
+
+ for (i = 0; i b; i++) {
+ wait_on_buffer(bh[i]);
+ if (!buffer_uptodate(bh[i]))
+ goto block_release;
+
+ avail = min(bytes, msblk-devblksize - offset);
+ memcpy(buff, bh[i]-b_data + offset, avail);
+ buff += avail;
+ bytes -= avail;
+ offset = 0;
+ put_bh(bh[i]);
+ }
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