Am Mo., 19. Juli 2021 um 16:48 Uhr schrieb Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>: > This tries to add tail packing inline read to iomap, which can support > several inline tail blocks. Similar to the previous approach, it cleans > post-EOF in one iteration. > > The write path remains untouched since EROFS cannot be used for testing. > It'd be better to be implemented if upcoming real users care rather than > leave untested dead code around. > > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Darrick J. Wong <djwong@xxxxxxxxxx> > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Cc: Andreas Gruenbacher <andreas.gruenbacher@xxxxxxxxx> > Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> > --- > v2: https://lore.kernel.org/r/YPLdSja%2F4FBsjss%2F@B-P7TQMD6M-0146.local/ > changes since v2: > - update suggestion from Christoph: > https://lore.kernel.org/r/YPVe41YqpfGLNsBS@xxxxxxxxxxxxx/ > > Hi Andreas, > would you mind test on the gfs2 side? Thanks in advance! > > Thanks, > Gao Xiang > > fs/iomap/buffered-io.c | 50 ++++++++++++++++++++++++++---------------- > fs/iomap/direct-io.c | 11 ++++++---- > 2 files changed, 38 insertions(+), 23 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 87ccb3438bec..cac8a88660d8 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -207,23 +207,22 @@ struct iomap_readpage_ctx { > > static void > iomap_read_inline_data(struct inode *inode, struct page *page, > - struct iomap *iomap) > + struct iomap *iomap, loff_t pos) > { > - size_t size = i_size_read(inode); > + unsigned int size, poff = offset_in_page(pos); > void *addr; > > - if (PageUptodate(page)) > - return; > - > - BUG_ON(page_has_private(page)); > - BUG_ON(page->index); > - BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data)); > + /* inline source data must be inside a single page */ > + BUG_ON(iomap->length > PAGE_SIZE - offset_in_page(iomap->inline_data)); > + /* handle tail-packing blocks cross the current page into the next */ > + size = min_t(unsigned int, iomap->length + pos - iomap->offset, > + PAGE_SIZE - poff); Hmm, so EROFS really does multi-page tail packing? This contradicts the comment and code in iomap_dio_inline_actor. > addr = kmap_atomic(page); > - memcpy(addr, iomap->inline_data, size); > - memset(addr + size, 0, PAGE_SIZE - size); > + memcpy(addr + poff, iomap->inline_data - iomap->offset + pos, size); > + memset(addr + poff + size, 0, PAGE_SIZE - poff - size); > kunmap_atomic(addr); > - SetPageUptodate(page); > + iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff); > } It's been said before, but iomap_read_inline_data should return PAGE_SIZE - poff, and no (void) casting when the return value is ignored. > static inline bool iomap_block_needs_zeroing(struct inode *inode, > @@ -246,18 +245,19 @@ 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; > - } > - > - /* zero post-eof blocks as the page may be mapped */ > iop = iomap_page_create(inode, page); > + /* needs to skip some leading uptodated blocks */ "needs to skip some leading uptodate blocks" > iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); > if (plen == 0) > goto done; > > + if (iomap->type == IOMAP_INLINE) { > + iomap_read_inline_data(inode, page, iomap, pos); > + plen = PAGE_SIZE - poff; > + goto done; > + } > + > + /* zero post-eof blocks as the page may be mapped */ > if (iomap_block_needs_zeroing(inode, iomap, pos)) { > zero_user(page, poff, plen); > iomap_set_range_uptodate(page, poff, plen); > @@ -589,6 +589,18 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, > return 0; > } > > +static int iomap_write_begin_inline(struct inode *inode, loff_t pos, > + struct page *page, struct iomap *srcmap) > +{ > + /* needs more work for the tailpacking case, disable for now */ > + if (WARN_ON_ONCE(pos != 0)) This should be a WARN_ON_ONCE(srcmap->offset != 0). Otherwise, something like: xfs_io -ft -c 'pwrite 1 2' will fail because pos will be 1. > + return -EIO; > + if (PageUptodate(page)) > + return 0; > + iomap_read_inline_data(inode, page, srcmap, pos); The above means that passing pos to iomap_read_inline_data here won't do the right thing, either. > + return 0; > +} > + > static int > iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, > struct page **pagep, struct iomap *iomap, struct iomap *srcmap) > @@ -618,7 +630,7 @@ 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_write_begin_inline(inode, pos, page, srcmap); > else if (iomap->flags & IOMAP_F_BUFFER_HEAD) > status = __block_write_begin_int(page, pos, len, NULL, srcmap); > else > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 9398b8c31323..ee6309967b77 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -379,22 +379,25 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length, > { > struct iov_iter *iter = dio->submit.iter; > size_t copied; > + void *dst = iomap->inline_data + pos - iomap->offset; > > - BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data)); > + /* inline data must be inside a single page */ > + BUG_ON(length > PAGE_SIZE - offset_in_page(iomap->inline_data)); > > 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_data + size - iomap->offset, > + 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; > -- > 2.24.4 > Thanks, Andreas
