Re: [PATCH 6/9] ext4: Provide ext4_do_writepages()

Ritesh Harjani (IBM)
2022-12-01T11:19:27Z

On 22/11/30 05:35PM, Jan Kara wrote:
> Provide ext4_do_writepages() function that takes mpage_da_data as an
> argument and make ext4_writepages() just a simple wrapper around it. No
> functional changes.
>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/ext4/inode.c | 96 +++++++++++++++++++++++++++----------------------
> 1 file changed, 54 insertions(+), 42 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 1cde20eb6500..fbea77ab470f 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1543,9 +1543,12 @@ void ext4_da_release_space(struct inode *inode, int to_free)
> */
>
> struct mpage_da_data {
> + /* These are input fields for ext4_do_writepages() */
> struct inode *inode;
> struct writeback_control *wbc;
> + unsigned int can_map:1; /* Can writepages call map blocks? */
>
> + /* These are internal state of ext4_do_writepages() */
> pgoff_t first_page; /* The first page to write */
> pgoff_t next_page; /* Current page to examine */
> pgoff_t last_page; /* Last page to examine */
> @@ -1557,7 +1560,6 @@ struct mpage_da_data {
> struct ext4_map_blocks map;
> struct ext4_io_submit io_submit; /* IO submission data */
> unsigned int do_map:1;
> - unsigned int can_map:1; /* Can writepages call map blocks? */
> unsigned int scanned_until_end:1;
> };
>
> @@ -2701,16 +2703,16 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
> return err;
> }
>
> -static int ext4_writepages(struct address_space *mapping,
> - struct writeback_control *wbc)
> +static int ext4_do_writepages(struct mpage_da_data *mpd)
> {
> + struct writeback_control *wbc = mpd->wbc;
> pgoff_t writeback_index = 0;
> long nr_to_write = wbc->nr_to_write;
> int range_whole = 0;
> int cycled = 1;
> handle_t *handle = NULL;
> - struct mpage_da_data mpd;
> - struct inode *inode = mapping->host;
> + struct inode *inode = mpd->inode;
> + struct address_space *mapping = inode->i_mapping;
> int needed_blocks, rsv_blocks = 0, ret = 0;
> struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
> struct blk_plug plug;
> @@ -2785,19 +2787,18 @@ static int ext4_writepages(struct address_space *mapping,
> writeback_index = mapping->writeback_index;
> if (writeback_index)
> cycled = 0;
> - mpd.first_page = writeback_index;
> - mpd.last_page = -1;
> + mpd->first_page = writeback_index;
> + mpd->last_page = -1;
> } else {
> - mpd.first_page = wbc->range_start >> PAGE_SHIFT;
> - mpd.last_page = wbc->range_end >> PAGE_SHIFT;
> + mpd->first_page = wbc->range_start >> PAGE_SHIFT;
> + mpd->last_page = wbc->range_end >> PAGE_SHIFT;
> }
>
> - mpd.inode = inode;
> - mpd.wbc = wbc;
> - ext4_io_submit_init(&mpd.io_submit, wbc);
> + ext4_io_submit_init(&mpd->io_submit, wbc);
> retry:
> if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
> - tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
> + tag_pages_for_writeback(mapping, mpd->first_page,
> + mpd->last_page);
> blk_start_plug(&plug);
>
> /*
> @@ -2806,28 +2807,27 @@ static int ext4_writepages(struct address_space *mapping,
> * in the block layer on device congestion while having transaction
> * started.
> */
> - mpd.do_map = 0;
> - mpd.scanned_until_end = 0;
> - mpd.can_map = 1;
> - mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
> - if (!mpd.io_submit.io_end) {
> + mpd->do_map = 0;
> + mpd->scanned_until_end = 0;
> + mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
> + if (!mpd->io_submit.io_end) {
> ret = -ENOMEM;
> goto unplug;
> }
> - ret = mpage_prepare_extent_to_map(&mpd);
> + ret = mpage_prepare_extent_to_map(mpd);
> /* Unlock pages we didn't use */
> - mpage_release_unused_pages(&mpd, false);
> + mpage_release_unused_pages(mpd, false);
> /* Submit prepared bio */
> - ext4_io_submit(&mpd.io_submit);
> - ext4_put_io_end_defer(mpd.io_submit.io_end);
> - mpd.io_submit.io_end = NULL;
> + ext4_io_submit(&mpd->io_submit);
> + ext4_put_io_end_defer(mpd->io_submit.io_end);
> + mpd->io_submit.io_end = NULL;
> if (ret < 0)
> goto unplug;
>
> - while (!mpd.scanned_until_end && wbc->nr_to_write > 0) {
> + while (!mpd->scanned_until_end && wbc->nr_to_write > 0) {
> /* For each extent of pages we use new io_end */
> - mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
> - if (!mpd.io_submit.io_end) {
> + mpd->io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
> + if (!mpd->io_submit.io_end) {
> ret = -ENOMEM;
> break;
> }
> @@ -2851,16 +2851,16 @@ static int ext4_writepages(struct address_space *mapping,
> "%ld pages, ino %lu; err %d", __func__,
> wbc->nr_to_write, inode->i_ino, ret);
> /* Release allocated io_end */
> - ext4_put_io_end(mpd.io_submit.io_end);
> - mpd.io_submit.io_end = NULL;
> + ext4_put_io_end(mpd->io_submit.io_end);
> + mpd->io_submit.io_end = NULL;
> break;
> }
> - mpd.do_map = 1;
> + mpd->do_map = 1;
>
> - trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
> - ret = mpage_prepare_extent_to_map(&mpd);
> - if (!ret && mpd.map.m_len)
> - ret = mpage_map_and_submit_extent(handle, &mpd,
> + trace_ext4_da_write_pages(inode, mpd->first_page, wbc);
> + ret = mpage_prepare_extent_to_map(mpd);
> + if (!ret && mpd->map.m_len)
> + ret = mpage_map_and_submit_extent(handle, mpd,
> &give_up_on_write);
> /*
> * Caution: If the handle is synchronous,
> @@ -2875,12 +2875,12 @@ static int ext4_writepages(struct address_space *mapping,
> if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
> ext4_journal_stop(handle);
> handle = NULL;
> - mpd.do_map = 0;
> + mpd->do_map = 0;
> }
> /* Unlock pages we didn't use */
> - mpage_release_unused_pages(&mpd, give_up_on_write);
> + mpage_release_unused_pages(mpd, give_up_on_write);
> /* Submit prepared bio */
> - ext4_io_submit(&mpd.io_submit);
> + ext4_io_submit(&mpd->io_submit);
>
> /*
> * Drop our io_end reference we got from init. We have
> @@ -2890,11 +2890,11 @@ static int ext4_writepages(struct address_space *mapping,
> * up doing unwritten extent conversion.
> */
> if (handle) {
> - ext4_put_io_end_defer(mpd.io_submit.io_end);
> + ext4_put_io_end_defer(mpd->io_submit.io_end);
> ext4_journal_stop(handle);
> } else
> - ext4_put_io_end(mpd.io_submit.io_end);
> - mpd.io_submit.io_end = NULL;
> + ext4_put_io_end(mpd->io_submit.io_end);
> + mpd->io_submit.io_end = NULL;
>
> if (ret == -ENOSPC && sbi->s_journal) {
> /*
> @@ -2914,8 +2914,8 @@ static int ext4_writepages(struct address_space *mapping,
> blk_finish_plug(&plug);
> if (!ret && !cycled && wbc->nr_to_write > 0) {
> cycled = 1;
> - mpd.last_page = writeback_index - 1;
> - mpd.first_page = 0;
> + mpd->last_page = writeback_index - 1;
> + mpd->first_page = 0;
> goto retry;
> }
>
> @@ -2925,7 +2925,7 @@ static int ext4_writepages(struct address_space *mapping,
> * Set the writeback_index so that range_cyclic
> * mode will write it back later
> */
> - mapping->writeback_index = mpd.first_page;
> + mapping->writeback_index = mpd->first_page;
>
> out_writepages:
> trace_ext4_writepages_result(inode, wbc, ret,
> @@ -2934,6 +2934,18 @@ static int ext4_writepages(struct address_space *mapping,
> return ret;
> }
>
> +static int ext4_writepages(struct address_space *mapping,
> + struct writeback_control *wbc)
> +{
> + struct mpage_da_data mpd = {
> + .inode = mapping->host,
> + .wbc = wbc,
> + .can_map = 1,
> + };
> +
> + return ext4_do_writepages(&mpd);
> +}
> +

Nice. Looks good to me.

Please feel free to add:
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>