On Wed, Nov 19, 2014 at 10:45:33PM -0800, Jaegeuk Kim wrote:
> On Thu, Nov 20, 2014 at 03:04:10PM +0900, Changman Lee wrote:
> > Hi Jaegeuk,
> >
> > We should call flush_dcache_page before kunmap because the purpose of the cache flush is to address aliasing problem related to virtual address.
>
> Oh, I just followed zero_user_segments below.
>
> static inline void zero_user_segments(struct page *page,
> unsigned start1, unsigned end1,
> unsigned start2, unsigned end2)
> {
> void *kaddr = kmap_atomic(page);
>
> BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
>
> if (end1 > start1)
> memset(kaddr + start1, 0, end1 - start1);
>
> if (end2 > start2)
> memset(kaddr + start2, 0, end2 - start2);
>
> kunmap_atomic(kaddr);
> flush_dcache_page(page);
> }
>
> Is this a wrong reference? Or, a bug?
>
Well.. Data in cache only have to be flushed until before other users read the data.
If so, it's not a bug.
> Anyway I modified as below.
>
> Thanks,
>
> >From 7cb7b27c8cd2efc8a31d79239bef5b41c6e79216 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> Date: Tue, 18 Nov 2014 10:50:21 -0800
> Subject: [PATCH] f2fs: call flush_dcache_page when the page was updated
>
> Whenever f2fs updates mapped pages, it needs to call flush_dcache_page.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/dir.c | 7 ++++++-
> fs/f2fs/inline.c | 2 ++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 5a49995..fabf4ee 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -287,8 +287,10 @@ void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
> f2fs_wait_on_page_writeback(page, type);
> de->ino = cpu_to_le32(inode->i_ino);
> set_de_type(de, inode);
> - if (!f2fs_has_inline_dentry(dir))
> + if (!f2fs_has_inline_dentry(dir)) {
> + flush_dcache_page(page);
> kunmap(page);
> + }
> set_page_dirty(page);
> dir->i_mtime = dir->i_ctime = CURRENT_TIME;
> mark_inode_dirty(dir);
> @@ -365,6 +367,7 @@ static int make_empty_dir(struct inode *inode,
> make_dentry_ptr(&d, (void *)dentry_blk, 1);
> do_make_empty_dir(inode, parent, &d);
>
> + flush_dcache_page(dentry_page);
> kunmap_atomic(dentry_blk);
>
> set_page_dirty(dentry_page);
> @@ -578,6 +581,7 @@ fail:
> update_inode_page(dir);
> clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
> }
> + flush_dcache_page(dentry_page);
> kunmap(dentry_page);
> f2fs_put_page(dentry_page, 1);
> return err;
> @@ -660,6 +664,7 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
> bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
> NR_DENTRY_IN_BLOCK,
> 0);
> + flush_dcache_page(page);
> kunmap(page); /* kunmap - pair of f2fs_find_entry */
> set_page_dirty(page);
>
> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index f26fb87..4291c1f 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -106,6 +106,7 @@ int f2fs_convert_inline_page(struct dnode_of_data *dn, struct page *page)
> src_addr = inline_data_addr(dn->inode_page);
> dst_addr = kmap_atomic(page);
> memcpy(dst_addr, src_addr, MAX_INLINE_DATA);
> + flush_dcache_page(page);
> kunmap_atomic(dst_addr);
> SetPageUptodate(page);
> no_update:
> @@ -357,6 +358,7 @@ static int f2fs_convert_inline_dir(struct inode *dir, struct page *ipage,
> memcpy(dentry_blk->filename, inline_dentry->filename,
> NR_INLINE_DENTRY * F2FS_SLOT_LEN);
>
> + flush_dcache_page(page);
> kunmap_atomic(dentry_blk);
> SetPageUptodate(page);
> set_page_dirty(page);
> --
> 2.1.1
>
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