Messages in this thread | | | Subject | Re: [PATCH v6] iomap: support tail packing inline read | From | Huang Jianan <> | Date | Fri, 23 Jul 2021 14:22:41 +0800 |
| |
Hi Xiang,
I have tested this patch based on the erofs dax support below, It works well for me.
https://git.kernel.org/pub/scm/linux/kernel/git/xiang/linux.git/log/?h=erofs/dax
Tested-by: Huang Jianan <huangjianan@oppo.com>
Thanks,
Jianan
On 2021/7/23 9:26, Gao Xiang wrote: > Hi Darrick, > > On Thu, Jul 22, 2021 at 09:51:09AM -0700, Darrick J. Wong wrote: >> On Thu, Jul 22, 2021 at 07:39:47AM +0200, Christoph Hellwig wrote: >>> I think some of the language here is confusing - mostly about tail >>> packing when we otherwise use inline data. Can you take a look at >>> the version below? This mostly cleans up the terminology, adds a >>> new helper to check the size, and removes the error on trying to >>> write with a non-zero pos, as it can be trivially supported now. >>> >>> --- >>> From 0f9c6ac6c2e372739b29195d25bebb8dd87e583a Mon Sep 17 00:00:00 2001 >>> From: Gao Xiang <hsiangkao@linux.alibaba.com> >>> Date: Thu, 22 Jul 2021 11:17:29 +0800 >>> Subject: iomap: make inline data support more flexible >>> >>> Add support for offsets into the inline data page at iomap->inline_data >>> to cater for the EROFS tailpackng case where a small data is stored >>> right after the inode. >> The commit message is a little misleading -- this adds support for >> inline data pages at nonzero (but page-aligned) file offsets, not file >> offsets into the page itself. I suggest: >> >> "Add support for reading inline data content into the page cache from >> nonzero page-aligned file offsets. This enables the EROFS tailpacking >> mode where the last few bytes of the file are stored right after the >> inode." >> >> The code changes look good to me. > Thanks for your suggestion. I've tested EROFS with no problem so far. > > I could update the commit message like this, what should I do next? > > Many thanks, > Gao Xiang > >> --D >> >>> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> >>> --- >>> fs/iomap/buffered-io.c | 35 ++++++++++++++++++----------------- >>> fs/iomap/direct-io.c | 10 ++++++---- >>> include/linux/iomap.h | 14 ++++++++++++++ >>> 3 files changed, 38 insertions(+), 21 deletions(-) >>> >>> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c >>> index 87ccb3438becd9..0597f5c186a33f 100644 >>> --- a/fs/iomap/buffered-io.c >>> +++ b/fs/iomap/buffered-io.c >>> @@ -205,25 +205,29 @@ struct iomap_readpage_ctx { >>> struct readahead_control *rac; >>> }; >>> >>> -static void >>> -iomap_read_inline_data(struct inode *inode, struct page *page, >>> - struct iomap *iomap) >>> +static int iomap_read_inline_data(struct inode *inode, struct page *page, >>> + struct iomap *iomap, loff_t pos) >>> { >>> - size_t size = i_size_read(inode); >>> + size_t size = iomap->length + iomap->offset - pos; >>> void *addr; >>> >>> if (PageUptodate(page)) >>> - return; >>> + return PAGE_SIZE; >>> >>> - BUG_ON(page_has_private(page)); >>> - BUG_ON(page->index); >>> - BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data)); >>> + /* inline data must start page aligned in the file */ >>> + if (WARN_ON_ONCE(offset_in_page(pos))) >>> + return -EIO; >>> + if (WARN_ON_ONCE(!iomap_inline_data_size_valid(iomap))) >>> + return -EIO; >>> + if (WARN_ON_ONCE(page_has_private(page))) >>> + return -EIO; >>> >>> addr = kmap_atomic(page); >>> - memcpy(addr, iomap->inline_data, size); >>> + memcpy(addr, iomap_inline_buf(iomap, pos), size); >>> memset(addr + size, 0, PAGE_SIZE - size); >>> kunmap_atomic(addr); >>> SetPageUptodate(page); >>> + return PAGE_SIZE; >>> } >>> >>> static inline bool iomap_block_needs_zeroing(struct inode *inode, >>> @@ -246,11 +250,8 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, >>> unsigned poff, plen; >>> sector_t sector; >>> >>> - if (iomap->type == IOMAP_INLINE) { >>> - WARN_ON_ONCE(pos); >>> - iomap_read_inline_data(inode, page, iomap); >>> - return PAGE_SIZE; >>> - } >>> + if (iomap->type == IOMAP_INLINE) >>> + return iomap_read_inline_data(inode, page, iomap, pos); >>> >>> /* zero post-eof blocks as the page may be mapped */ >>> iop = iomap_page_create(inode, page); >>> @@ -618,14 +619,14 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, >>> } >>> >>> if (srcmap->type == IOMAP_INLINE) >>> - iomap_read_inline_data(inode, page, srcmap); >>> + status = iomap_read_inline_data(inode, page, srcmap, pos); >>> else if (iomap->flags & IOMAP_F_BUFFER_HEAD) >>> status = __block_write_begin_int(page, pos, len, NULL, srcmap); >>> else >>> status = __iomap_write_begin(inode, pos, len, flags, page, >>> srcmap); >>> >>> - if (unlikely(status)) >>> + if (unlikely(status < 0)) >>> goto out_unlock; >>> >>> *pagep = page; >>> @@ -675,7 +676,7 @@ static size_t iomap_write_end_inline(struct inode *inode, struct page *page, >>> >>> flush_dcache_page(page); >>> addr = kmap_atomic(page); >>> - memcpy(iomap->inline_data + pos, addr + pos, copied); >>> + memcpy(iomap_inline_buf(iomap, pos), addr + pos, copied); >>> kunmap_atomic(addr); >>> >>> mark_inode_dirty(inode); >>> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c >>> index 9398b8c31323b3..a6aaea2764a55f 100644 >>> --- a/fs/iomap/direct-io.c >>> +++ b/fs/iomap/direct-io.c >>> @@ -378,23 +378,25 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length, >>> struct iomap_dio *dio, struct iomap *iomap) >>> { >>> struct iov_iter *iter = dio->submit.iter; >>> + void *dst = iomap_inline_buf(iomap, pos); >>> size_t copied; >>> >>> - BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data)); >>> + if (WARN_ON_ONCE(!iomap_inline_data_size_valid(iomap))) >>> + return -EIO; >>> >>> if (dio->flags & IOMAP_DIO_WRITE) { >>> loff_t size = inode->i_size; >>> >>> if (pos > size) >>> - memset(iomap->inline_data + size, 0, pos - size); >>> - copied = copy_from_iter(iomap->inline_data + pos, length, iter); >>> + memset(iomap_inline_buf(iomap, size), 0, pos - size); >>> + copied = copy_from_iter(dst, length, iter); >>> if (copied) { >>> if (pos + copied > size) >>> i_size_write(inode, pos + copied); >>> mark_inode_dirty(inode); >>> } >>> } else { >>> - copied = copy_to_iter(iomap->inline_data + pos, length, iter); >>> + copied = copy_to_iter(dst, length, iter); >>> } >>> dio->size += copied; >>> return copied; >>> diff --git a/include/linux/iomap.h b/include/linux/iomap.h >>> index 479c1da3e2211e..5efae7153912ed 100644 >>> --- a/include/linux/iomap.h >>> +++ b/include/linux/iomap.h >>> @@ -97,6 +97,20 @@ iomap_sector(struct iomap *iomap, loff_t pos) >>> return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT; >>> } >>> >>> +static inline void *iomap_inline_buf(const struct iomap *iomap, loff_t pos) >>> +{ >>> + return iomap->inline_data - iomap->offset + pos; >>> +} >>> + >>> +/* >>> + * iomap->inline_data is a potentially kmapped page, ensure it never crosseѕ a >>> + * page boundary. >>> + */ >>> +static inline bool iomap_inline_data_size_valid(const struct iomap *iomap) >>> +{ >>> + return iomap->length <= PAGE_SIZE - offset_in_page(iomap->inline_data); >>> +} >>> + >>> /* >>> * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare >>> * and page_done will be called for each page written to. This only applies to >>> -- >>> 2.30.2 >>>
| |