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We use the generic infrastructure for this, by tracking pages we created and calling write_drop_cached_pages() to issue writeback and prune those pages. Signed-off-by: Jens Axboe --- fs/iomap/buffered-io.c | 72 +++++++++++++++++++++++++++++++++++------- include/linux/iomap.h | 1 + 2 files changed, 62 insertions(+), 11 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 9b5b770ca4c7..3a18a6af8cb3 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "trace.h" =20 #include "../internal.h" @@ -566,6 +567,7 @@ EXPORT_SYMBOL_GPL(iomap_migrate_page); =20 enum { IOMAP_WRITE_F_UNSHARE =3D (1 << 0), + IOMAP_WRITE_F_UNCACHED =3D (1 << 1), }; =20 static void @@ -643,6 +645,7 @@ iomap_write_begin(struct inode *inode, loff_t pos, un= signed len, unsigned flags, struct page **pagep, struct iomap *iomap, struct iomap *srcmap) { const struct iomap_page_ops *page_ops =3D iomap->page_ops; + unsigned aop_flags; struct page *page; int status =3D 0; =20 @@ -659,8 +662,11 @@ iomap_write_begin(struct inode *inode, loff_t pos, u= nsigned len, unsigned flags, return status; } =20 + aop_flags =3D AOP_FLAG_NOFS; + if (flags & IOMAP_UNCACHED) + aop_flags |=3D AOP_FLAG_UNCACHED; page =3D grab_cache_page_write_begin(inode->i_mapping, pos >> PAGE_SHIF= T, - AOP_FLAG_NOFS); + aop_flags); if (!page) { status =3D -ENOMEM; goto out_no_page; @@ -670,9 +676,14 @@ iomap_write_begin(struct inode *inode, loff_t pos, u= nsigned len, unsigned flags, iomap_read_inline_data(inode, page, srcmap); else if (iomap->flags & IOMAP_F_BUFFER_HEAD) status =3D __block_write_begin_int(page, pos, len, NULL, srcmap); - else - status =3D __iomap_write_begin(inode, pos, len, flags, page, + else { + unsigned wb_flags =3D 0; + + if (flags & IOMAP_UNCACHED) + wb_flags =3D IOMAP_WRITE_F_UNCACHED; + status =3D __iomap_write_begin(inode, pos, len, wb_flags, page, srcmap); + } =20 if (unlikely(status)) goto out_unlock; @@ -796,19 +807,27 @@ iomap_write_end(struct inode *inode, loff_t pos, un= signed len, unsigned copied, return ret; } =20 +#define GPW_PAGE_BATCH 16 + static loff_t iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *= data, unsigned flags, struct iomap *iomap, struct iomap *srcmap) { + struct address_space *mapping =3D inode->i_mapping; struct iov_iter *i =3D data; + struct pagevec pvec; long status =3D 0; ssize_t written =3D 0; =20 + pagevec_init(&pvec); + do { struct page *page; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ + bool drop_page =3D false; /* drop page after IO */ + unsigned lflags =3D flags; =20 offset =3D offset_in_page(pos); bytes =3D min_t(unsigned long, PAGE_SIZE - offset, @@ -832,10 +851,17 @@ iomap_write_actor(struct inode *inode, loff_t pos, = loff_t length, void *data, break; } =20 - status =3D iomap_write_begin(inode, pos, bytes, 0, &page, iomap, - srcmap); - if (unlikely(status)) +retry: + status =3D iomap_write_begin(inode, pos, bytes, lflags, &page, + iomap, srcmap); + if (unlikely(status)) { + if (status =3D=3D -ENOMEM && (lflags & IOMAP_UNCACHED)) { + drop_page =3D true; + lflags &=3D ~IOMAP_UNCACHED; + goto retry; + } break; + } =20 if (mapping_writably_mapped(inode->i_mapping)) flush_dcache_page(page); @@ -844,10 +870,16 @@ iomap_write_actor(struct inode *inode, loff_t pos, = loff_t length, void *data, =20 flush_dcache_page(page); =20 + if (drop_page) + get_page(page); + status =3D iomap_write_end(inode, pos, bytes, copied, page, iomap, srcmap); - if (unlikely(status < 0)) + if (unlikely(status < 0)) { + if (drop_page) + put_page(page); break; + } copied =3D status; =20 cond_resched(); @@ -864,15 +896,29 @@ iomap_write_actor(struct inode *inode, loff_t pos, = loff_t length, void *data, */ bytes =3D min_t(unsigned long, PAGE_SIZE - offset, iov_iter_single_seg_count(i)); + if (drop_page) + put_page(page); goto again; } + + if (drop_page && + ((pos >> PAGE_SHIFT) !=3D ((pos + copied) >> PAGE_SHIFT))) { + if (!pagevec_add(&pvec, page)) + write_drop_cached_pages(&pvec, mapping); + } else { + if (drop_page) + put_page(page); + balance_dirty_pages_ratelimited(inode->i_mapping); + } + pos +=3D copied; written +=3D copied; length -=3D copied; - - balance_dirty_pages_ratelimited(inode->i_mapping); } while (iov_iter_count(i) && length); =20 + if (pagevec_count(&pvec)) + write_drop_cached_pages(&pvec, mapping); + return written ? written : status; } =20 @@ -882,10 +928,14 @@ iomap_file_buffered_write(struct kiocb *iocb, struc= t iov_iter *iter, { struct inode *inode =3D iocb->ki_filp->f_mapping->host; loff_t pos =3D iocb->ki_pos, ret =3D 0, written =3D 0; + unsigned flags =3D IOMAP_WRITE; + + if (iocb->ki_flags & IOCB_UNCACHED) + flags |=3D IOMAP_UNCACHED; =20 while (iov_iter_count(iter)) { - ret =3D iomap_apply(inode, pos, iov_iter_count(iter), - IOMAP_WRITE, ops, iter, iomap_write_actor); + ret =3D iomap_apply(inode, pos, iov_iter_count(iter), flags, + ops, iter, iomap_write_actor); if (ret <=3D 0) break; pos +=3D ret; diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 61fcaa3904d4..833dd43507ac 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -121,6 +121,7 @@ struct iomap_page_ops { #define IOMAP_FAULT (1 << 3) /* mapping for page fault */ #define IOMAP_DIRECT (1 << 4) /* direct I/O */ #define IOMAP_NOWAIT (1 << 5) /* do not block */ +#define IOMAP_UNCACHED (1 << 6) =20 struct iomap_ops { /* --=20 2.24.0