On 02/28, heyunlei wrote:
> Hi Jaegeuk,
>
> On 2017/2/28 7:08, Jaegeuk Kim wrote:
> > On 02/27, Yunlei He wrote:
> > > This patch add a function to modify discard command if one segment
> > > reuse before discard. Split this segment from multi-segments discard
> > > range, and discard the left bigger range.
> >
> > Now MAX_DISCARD_BLOCKS() is set to section size, so there will be no
> > multi-sections discard range. Am I missing some cases?
>
> I think MAX_DISCARD_BLOCKS() just limit small discard and fstrim, f2fs
>
> can still send multi-segments discard range if prefree segments is continuous.
Got it.
Comments below.
> > > Signed-off-by: Yunlei He <heyun...@huawei.com>
> > > ---
> > > fs/f2fs/segment.c | 18 +++++++++++++++++-
> > > 1 file changed, 17 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 9006d8e..5af736b 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -672,6 +672,22 @@ static void __remove_discard_cmd(struct f2fs_sb_info
> > > *sbi, struct discard_cmd *d
> > > kmem_cache_free(discard_cmd_slab, dc);
> > > }
> > >
> > > +static void __modify_discard_cmd(struct f2fs_sb_info *sbi, struct
> > > discard_cmd *dc, block_t blkaddr)
How about modifying the name "modify" to "punch"?
> > > +{
> > > + block_t end_block = START_BLOCK(sbi, GET_SEGNO(sbi, blkaddr) + 1);
> > > +
> > > + if (dc->lstart + dc->len <= end_block) {
> > > + __remove_discard_cmd(sbi, dc);
> > > + return;
> > > + }
> > > +
> > > + if (dc->lstart - blkaddr < dc->lstart + dc->len - end_block) {
The blkaddr is larger than or equal to dc->lstart all the time, resulting in
overflow?
Thanks,
> > > + dc->lstart = end_block;
> > > + dc->len -= (end_block - dc->lstart);
> > > + } else
> > > + dc->len = blkaddr - dc->lstart;
> > > +}
> > > +
> > > /* This should be covered by global mutex, &sit_i->sentry_lock */
> > > void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
> > > {
> > > @@ -699,7 +715,7 @@ void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi,
> > > block_t blkaddr)
> > > if (dc->state == D_SUBMIT)
> > > wait_for_completion_io(&dc->wait);
> > > else
> > > - __remove_discard_cmd(sbi, dc);
> > > + __modify_discard_cmd(sbi, dc, blkaddr);
> > > }
> > > }
> > > blk_finish_plug(&plug);
> > > --
> > > 2.10.1
> >
> > .
> >
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