libext2fs: factor out I/O buffer allocation

Create a new function, io_channel_alloc_buf() which allocates I/O
buffers with appropriate alignment if we are using direct I/O.  The
original code was sometimes using a larger alignment factor than
necessary, and would always request an aligned memory buffer even when
it was not necessary since the block device was not opened with
O_DIRECT.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
index 95b8de3..1894fb8 100644 (file)
--- a/lib/ext2fs/ext2_io.h
+++ b/lib/ext2fs/ext2_io.h
@@ -122,6 +122,8 @@ extern errcode_t io_channel_write_blk64(io_channel channel,
 extern errcode_t io_channel_discard(io_channel channel,
                                    unsigned long long block,
                                    unsigned long long count);
+extern errcode_t io_channel_alloc_buf(io_channel channel,
+                                     int count, void *ptr);
 
 /* unix_io.c */
 extern io_manager unix_io_manager;

diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
index 6c524ff..77fc447 100644 (file)
--- a/lib/ext2fs/inode.c
+++ b/lib/ext2fs/inode.c
@@ -157,8 +157,8 @@ errcode_t ext2fs_open_inode_scan(ext2_filsys fs, int buffer_blocks,
                         (fs->blocksize / scan->inode_size - 1)) *
                        scan->inode_size / fs->blocksize;
        }
-       retval = ext2fs_get_memalign(scan->inode_buffer_blocks * fs->blocksize,
-                                    fs->blocksize, &scan->inode_buffer);
+       retval = io_channel_alloc_buf(fs->io, scan->inode_buffer_blocks,
+                                     &scan->inode_buffer);
        scan->done_group = 0;
        scan->done_group_data = 0;
        scan->bad_block_ptr = 0;

diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index 25df59e..34e4859 100644 (file)
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -111,3 +111,20 @@ errcode_t io_channel_discard(io_channel channel, unsigned long long block,
 
        return EXT2_ET_UNIMPLEMENTED;
 }
+
+errcode_t io_channel_alloc_buf(io_channel io, int count, void *ptr)
+{
+       size_t  size;
+
+       if (count == 0)
+               size = io->block_size;
+       else if (count > 0)
+               size = io->block_size * count;
+       else
+               size = -count;
+
+       if (io->align)
+               return ext2fs_get_memalign(size, io->align, ptr);
+       else
+               return ext2fs_get_mem(size, ptr);
+}

diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 220d954..482e4ab 100644 (file)
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -144,7 +144,7 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
                goto cleanup;
        fs->image_io = fs->io;
        fs->io->app_data = fs;
-       retval = ext2fs_get_memalign(SUPERBLOCK_SIZE, 512, &fs->super);
+       retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
        if (retval)
                goto cleanup;
        if (flags & EXT2_FLAG_IMAGE_FILE) {

diff --git a/lib/ext2fs/rw_bitmaps.c b/lib/ext2fs/rw_bitmaps.c
index 81e09c0..53f6ec4 100644 (file)
--- a/lib/ext2fs/rw_bitmaps.c
+++ b/lib/ext2fs/rw_bitmaps.c
@@ -53,8 +53,7 @@ static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
        inode_nbytes = block_nbytes = 0;
        if (do_block) {
                block_nbytes = EXT2_CLUSTERS_PER_GROUP(fs->super) / 8;
-               retval = ext2fs_get_memalign(fs->blocksize, fs->blocksize,
-                                            &block_buf);
+               retval = io_channel_alloc_buf(fs->io, 0, &block_buf);
                if (retval)
                        goto errout;
                memset(block_buf, 0xff, fs->blocksize);
@@ -62,8 +61,7 @@ static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
        if (do_inode) {
                inode_nbytes = (size_t)
                        ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
-               retval = ext2fs_get_memalign(fs->blocksize, fs->blocksize,
-                                            &inode_buf);
+               retval = io_channel_alloc_buf(fs->io, 0, &inode_buf);
                if (retval)
                        goto errout;
                memset(inode_buf, 0xff, fs->blocksize);
@@ -186,13 +184,7 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
                retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
                if (retval)
                        goto cleanup;
-               if (do_image)
-                       retval = ext2fs_get_mem(fs->blocksize, &block_bitmap);
-               else
-                       retval = ext2fs_get_memalign(fs->blocksize,
-                                                    fs->blocksize,
-                                                    &block_bitmap);
-                       
+               retval = io_channel_alloc_buf(fs->io, 0, &block_bitmap);
                if (retval)
                        goto cleanup;
        } else
@@ -205,7 +197,7 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
                retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
                if (retval)
                        goto cleanup;
-               retval = ext2fs_get_mem(fs->blocksize, &inode_bitmap);
+               retval = io_channel_alloc_buf(fs->io, 0, &inode_bitmap);
                if (retval)
                        goto cleanup;
        } else

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 8319eba..2ce0563 100644 (file)
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -316,17 +316,14 @@ static errcode_t alloc_cache(io_channel channel,
                cache->in_use = 0;
                if (cache->buf)
                        ext2fs_free_mem(&cache->buf);
-               retval = ext2fs_get_memalign(channel->block_size,
-                                            channel->align, &cache->buf);
+               retval = io_channel_alloc_buf(channel, 0, &cache->buf);
                if (retval)
                        return retval;
        }
        if (channel->align) {
                if (data->bounce)
                        ext2fs_free_mem(&data->bounce);
-               retval = ext2fs_get_memalign(channel->block_size,
-                                            channel->align,
-                                            &data->bounce);
+               retval = io_channel_alloc_buf(channel, 0, &data->bounce);
        }
        return retval;
 }