Hi Christoph, 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. >
Many thanks for your time and hard work on revising this again. I'm fine with this version and the update for iomap_write_begin(), and I will do test hours later as I said before. Hopefully this version could be confirmed by Andreas on the gfs2 side as well. Thanks, Gao Xiang > --- > From 0f9c6ac6c2e372739b29195d25bebb8dd87e583a Mon Sep 17 00:00:00 2001 > From: Gao Xiang <[email protected]> > 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. > > Signed-off-by: Gao Xiang <[email protected]> > --- > 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
