On Mon, Aug 24, 2020 at 03:55:10PM +0100, Matthew Wilcox (Oracle) wrote: > Pass the full length to iomap_zero() and dax_iomap_zero(), and have > them return how many bytes they actually handled. This is preparatory > work for handling THP, although it looks like DAX could actually take > advantage of it if there's a larger contiguous area. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > --- > fs/dax.c | 13 ++++++------- > fs/iomap/buffered-io.c | 33 +++++++++++++++------------------ > include/linux/dax.h | 3 +-- > 3 files changed, 22 insertions(+), 27 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 95341af1a966..f2b912cb034e 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1037,18 +1037,18 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, > return ret; > } > > -int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size, > - struct iomap *iomap) > +loff_t dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) Sorry for my ultra-slow response to this. The u64 length seems ok to me (or uint64_t, I don't care all /that/ much), but using loff_t as a return type bothers me because I see that and think that this function is returning a new file offset, e.g. (pos + number of bytes zeroed). So please, let's use s64 or something that isn't so misleading. FWIW, Linus also[0] doesn't[1] like using loff_t for the number of bytes copied. --D [0] https://lore.kernel.org/linux-fsdevel/CAHk-=wgcPAfOSigMf0xwaGfVjw413XN3UPATwYWHrss+QuivhQ@xxxxxxxxxxxxxx/ [1] https://lore.kernel.org/linux-fsdevel/CAHk-=wgvROUnrEVADVR_zTHY8NmYo-_jVjV37O1MdDm2de+Lmw@xxxxxxxxxxxxxx/ > { > sector_t sector = iomap_sector(iomap, pos & PAGE_MASK); > pgoff_t pgoff; > long rc, id; > void *kaddr; > bool page_aligned = false; > - > + unsigned offset = offset_in_page(pos); > + unsigned size = min_t(u64, PAGE_SIZE - offset, length); > > if (IS_ALIGNED(sector << SECTOR_SHIFT, PAGE_SIZE) && > - IS_ALIGNED(size, PAGE_SIZE)) > + (size == PAGE_SIZE)) > page_aligned = true; > > rc = bdev_dax_pgoff(iomap->bdev, sector, PAGE_SIZE, &pgoff); > @@ -1058,8 +1058,7 @@ int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size, > id = dax_read_lock(); > > if (page_aligned) > - rc = dax_zero_page_range(iomap->dax_dev, pgoff, > - size >> PAGE_SHIFT); > + rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1); > else > rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL); > if (rc < 0) { > @@ -1072,7 +1071,7 @@ int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size, > dax_flush(iomap->dax_dev, kaddr + offset, size); > } > dax_read_unlock(id); > - return 0; > + return size; > } > > static loff_t > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 7f618ab4b11e..2dba054095e8 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -901,11 +901,13 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len, > } > EXPORT_SYMBOL_GPL(iomap_file_unshare); > > -static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, > - unsigned bytes, struct iomap *iomap, struct iomap *srcmap) > +static loff_t iomap_zero(struct inode *inode, loff_t pos, u64 length, > + struct iomap *iomap, struct iomap *srcmap) > { > struct page *page; > int status; > + unsigned offset = offset_in_page(pos); > + unsigned bytes = min_t(u64, PAGE_SIZE - offset, length); > > status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap); > if (status) > @@ -917,38 +919,33 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, > return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap); > } > > -static loff_t > -iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, > - void *data, struct iomap *iomap, struct iomap *srcmap) > +static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos, > + loff_t length, void *data, struct iomap *iomap, > + struct iomap *srcmap) > { > bool *did_zero = data; > loff_t written = 0; > - int status; > > /* already zeroed? we're done. */ > if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) > - return count; > + return length; > > do { > - unsigned offset, bytes; > - > - offset = offset_in_page(pos); > - bytes = min_t(loff_t, PAGE_SIZE - offset, count); > + loff_t bytes; > > if (IS_DAX(inode)) > - status = dax_iomap_zero(pos, offset, bytes, iomap); > + bytes = dax_iomap_zero(pos, length, iomap); > else > - status = iomap_zero(inode, pos, offset, bytes, iomap, > - srcmap); > - if (status < 0) > - return status; > + bytes = iomap_zero(inode, pos, length, iomap, srcmap); > + if (bytes < 0) > + return bytes; > > pos += bytes; > - count -= bytes; > + length -= bytes; > written += bytes; > if (did_zero) > *did_zero = true; > - } while (count > 0); > + } while (length > 0); > > return written; > } > diff --git a/include/linux/dax.h b/include/linux/dax.h > index 6904d4e0b2e0..80f17946f940 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -214,8 +214,7 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf, > int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index); > int dax_invalidate_mapping_entry_sync(struct address_space *mapping, > pgoff_t index); > -int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size, > - struct iomap *iomap); > +loff_t dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap); > static inline bool dax_mapping(struct address_space *mapping) > { > return mapping->host && IS_DAX(mapping->host); > -- > 2.28.0 >
