On Wed, Feb 22, 2017 at 08:28:47PM -0800, Jaegeuk Kim wrote:
> This patch adds MAX_DISCARD_BLOCKS() to avoid issuing too much large single
> discard command.
Needs an explanation in the code on why this number was chosen.
In doubt I suspect it should be a quirk in the driver for the device,
and not something decided by the fs.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/f2fs.h | 3 ++-
> fs/f2fs/segment.c | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d076b94530bc..5f3fe97df055 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -133,7 +133,8 @@ enum {
> (SM_I(sbi)->trim_sections * (sbi)->segs_per_sec)
> #define BATCHED_TRIM_BLOCKS(sbi) \
> (BATCHED_TRIM_SEGMENTS(sbi) << (sbi)->log_blocks_per_seg)
> -
> +#define MAX_DISCARD_BLOCKS(sbi) \
> + ((1 << (sbi)->log_blocks_per_seg) * (sbi)->segs_per_sec)
> #define DISCARD_ISSUE_RATE 8
> #define DEF_CP_INTERVAL 60 /* 60 secs */
> #define DEF_IDLE_INTERVAL 5 /* 5 secs */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index fe434cd872b4..567019940e9b 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -886,7 +886,8 @@ static void __add_discard_entry(struct f2fs_sb_info *sbi,
> if (!list_empty(head)) {
> last = list_last_entry(head, struct discard_entry, list);
> if (START_BLOCK(sbi, cpc->trim_start) + start ==
> - last->blkaddr + last->len) {
> + last->blkaddr + last->len &&
> + last->len < MAX_DISCARD_BLOCKS(sbi)) {
> last->len += end - start;
> goto done;
> }
> --
> 2.11.0
>
---end quoted text---
