On Thu, 14 Aug 2014 17:03:59 +0200 (CEST), Lukáš Czerner <lczerner@xxxxxxxxxx> wrote:
> On Wed, 13 Aug 2014, Dmitry Monakhov wrote:
>
> > Date: Wed, 13 Aug 2014 19:45:10 +0400
> > From: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> > To: linux-ext4@xxxxxxxxxxxxxxx
> > Cc: tytso@xxxxxxx, Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> > Subject: [PATCH 1/2] Use ext4_ext_next_allocated_block instead of
> > mext_next_extent
> >
> > This allow to make mext_next_extent static.
> >
> > Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
> > ---
> > fs/ext4/ext4.h | 2 --
> > fs/ext4/extents.c | 18 ++++++------------
> > fs/ext4/move_extent.c | 2 +-
> > 3 files changed, 7 insertions(+), 15 deletions(-)
> >
> > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> > index 5b19760..f8d85f7 100644
> > --- a/fs/ext4/ext4.h
> > +++ b/fs/ext4/ext4.h
> > @@ -2739,8 +2739,6 @@ extern void ext4_double_up_write_data_sem(struct inode *orig_inode,
> > extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
> > __u64 start_orig, __u64 start_donor,
> > __u64 len, __u64 *moved_len);
> > -extern int mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
> > - struct ext4_extent **extent);
> >
> > /* page-io.c */
> > extern int __init ext4_init_pageio(void);
> > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > index 76c2df3..2e38ecb 100644
> > --- a/fs/ext4/extents.c
> > +++ b/fs/ext4/extents.c
> > @@ -5304,7 +5304,7 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> > struct ext4_ext_path *path;
> > int ret = 0, depth;
> > struct ext4_extent *extent;
> > - ext4_lblk_t stop_block, current_block;
> > + ext4_lblk_t stop_block;
> > ext4_lblk_t ex_start, ex_end;
> >
> > /* Let path point to the last extent */
> > @@ -5365,18 +5365,12 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> > (unsigned long) start);
> > return -EIO;
> > }
> > -
> > - current_block = le32_to_cpu(extent->ee_block);
> > - if (start > current_block) {
> > + if (start > le32_to_cpu(extent->ee_block)) {
> > /* Hole, move to the next extent */
> > - ret = mext_next_extent(inode, path, &extent);
> > - if (ret != 0) {
> > - ext4_ext_drop_refs(path);
> > - kfree(path);
> > - if (ret == 1)
> > - ret = 0;
> > - break;
> > - }
> > + start = ext4_ext_next_allocated_block(path);
> > + ext4_ext_drop_refs(path);
> > + kfree(path);
> > + continue;
>
> It seems to me that this will affect the performance of the shift as
> we would potentially need to do more iteration, because the current
> code would update the "extents" to the actual next extent and then
> then do the shift right away, while your solution just finds the
> next block and then jumps at the beginning of the loop to generate
> path and find the extent all over again. What do you think ?
Agree, leaf case must be optimized:
if (extent < EXT_LAST_EXTENT(path[depth].p_hdr))
path[depth].p_ext++;
Will be back with new version.
>
> -Lukas
>
> > }
> > ret = ext4_ext_shift_path_extents(path, shift, inode,
> > handle, &start);
> > diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> > index 671a74b..123a51b 100644
> > --- a/fs/ext4/move_extent.c
> > +++ b/fs/ext4/move_extent.c
> > @@ -76,7 +76,7 @@ copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
> > * ext4_ext_path structure refers to the last extent, or a negative error
> > * value on failure.
> > */
> > -int
> > +static int
> > mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
> > struct ext4_extent **extent)
> > {
> >
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