On Dec 13, 2014, at 09:24, Theodore Ts'o <tytso@xxxxxxx> wrote:
>
> This is my replacement patch.
>
> - Ted
>
> commit 0a92af260da381e2581074871707e487728373ad
> Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Date: Fri Dec 12 18:27:12 2014 -0500
>
> libext2fs: use a dynamically sized block zeroing buffer
>
> Dynamically grow the block zeroing buffer to a maximum of 4MB, and
> allow callers to provide their own zeroed buffer in
> ext2fs_zero_blocks2().
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
>
> diff --git a/lib/ext2fs/mkjournal.c b/lib/ext2fs/mkjournal.c
> index e8f8b30..fcc6741 100644
> --- a/lib/ext2fs/mkjournal.c
> +++ b/lib/ext2fs/mkjournal.c
> @@ -148,12 +148,13 @@ errfree:
> * attempt to free the static zeroizing buffer. (This is to keep
> * programs that check for memory leaks happy.)
> */
> -#define STRIDE_LENGTH (4194304 / fs->blocksize)
> +#define MAX_STRIDE_LENGTH (4194304 / (int) fs->blocksize)
> errcode_t ext2fs_zero_blocks2(ext2_filsys fs, blk64_t blk, int num,
> blk64_t *ret_blk, int *ret_count)
> {
> int j, count;
> - static char *buf;
> + static void *buf;
> + static int stride_length;
> errcode_t retval;
>
> /* If fs is null, clean up the static buffer and return */
> @@ -164,24 +165,36 @@ errcode_t ext2fs_zero_blocks2(ext2_filsys fs, blk64_t blk, int num,
> }
> return 0;
> }
> +
> + /* Deal with zeroing less than 1 block */
> + if (num <= 0)
> + return 0;
> +
> /* Allocate the zeroizing buffer if necessary */
> - if (!buf) {
> - buf = malloc(fs->blocksize * STRIDE_LENGTH);
> - if (!buf)
> - return ENOMEM;
> - memset(buf, 0, fs->blocksize * STRIDE_LENGTH);
> + if (num > stride_length && stride_length < MAX_STRIDE_LENGTH) {
> + void *p;
> + int new_stride = num;
> +
> + if (new_stride > MAX_STRIDE_LENGTH)
> + new_stride = MAX_STRIDE_LENGTH;
> + p = realloc(buf, fs->blocksize * new_stride);
> + if (!p)
> + return EXT2_ET_NO_MEMORY;
Shouldn't this continue using the original buf/num if this realloc fails?
Cheers, Andreas
> + buf = p;
> + stride_length = new_stride;
> + memset(buf, 0, fs->blocksize * stride_length);
> }
> /* OK, do the write loop */
> j=0;
> while (j < num) {
> - if (blk % STRIDE_LENGTH) {
> - count = STRIDE_LENGTH - (blk % STRIDE_LENGTH);
> + if (blk % stride_length) {
> + count = stride_length - (blk % stride_length);
> if (count > (num - j))
> count = num - j;
> } else {
> count = num - j;
> - if (count > STRIDE_LENGTH)
> - count = STRIDE_LENGTH;
> + if (count > stride_length)
> + count = stride_length;
> }
> retval = io_channel_write_blk64(fs->io, blk, count, buf);
> if (retval) {
> --
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