On Wed, May 23, 2018 at 04:46:46PM +0200, Christoph Hellwig wrote:
> Switch to using the iomap_page structure for checking sub-page uptodate
> status and track sub-page I/O completion status, and remove large
> quantities of boilerplate code working around buffer heads.
>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
> ---
> fs/xfs/xfs_aops.c | 536 +++++++--------------------------------------
> fs/xfs/xfs_buf.h | 1 -
> fs/xfs/xfs_iomap.c | 3 -
> fs/xfs/xfs_super.c | 2 +-
> fs/xfs/xfs_trace.h | 18 +-
> 5 files changed, 79 insertions(+), 481 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index efa2cbb27d67..d279929e53fb 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
...
> @@ -768,7 +620,7 @@ xfs_aops_discard_page(
> int error;
>
> if (XFS_FORCED_SHUTDOWN(mp))
> - goto out_invalidate;
> + goto out;
>
> xfs_alert(mp,
> "page discard on page "PTR_FMT", inode 0x%llx, offset %llu.",
> @@ -778,15 +630,15 @@ xfs_aops_discard_page(
> PAGE_SIZE / i_blocksize(inode));
> if (error && !XFS_FORCED_SHUTDOWN(mp))
> xfs_alert(mp, "page discard unable to remove delalloc
> mapping.");
> -out_invalidate:
> - xfs_vm_invalidatepage(page, 0, PAGE_SIZE);
> +out:
> + iomap_invalidatepage(page, 0, PAGE_SIZE);
All this does is lose the tracepoint. I don't think this call needs to
change. The rest looks Ok to me, but I still need to run some tests on
the whole thing.
Brian
> }
>
> /*
> * We implement an immediate ioend submission policy here to avoid needing to
> * chain multiple ioends and hence nest mempool allocations which can violate
> * forward progress guarantees we need to provide. The current ioend we are
> - * adding buffers to is cached on the writepage context, and if the new
> buffer
> + * adding blocks to is cached on the writepage context, and if the new block
> * does not append to the cached ioend it will create a new ioend and cache
> that
> * instead.
> *
> @@ -807,41 +659,28 @@ xfs_writepage_map(
> uint64_t end_offset)
> {
> LIST_HEAD(submit_list);
> + struct iomap_page *iop = to_iomap_page(page);
> + unsigned len = i_blocksize(inode);
> struct xfs_ioend *ioend, *next;
> - struct buffer_head *bh = NULL;
> - ssize_t len = i_blocksize(inode);
> - int error = 0;
> - int count = 0;
> - loff_t file_offset; /* file offset of page */
> - unsigned poffset; /* offset into page */
> + int error = 0, count = 0, i;
> + u64 file_offset; /* file offset of page */
>
> - if (page_has_buffers(page))
> - bh = page_buffers(page);
> + ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
> + ASSERT(!iop || atomic_read(&iop->write_count) == 0);
>
> /*
> - * Walk the blocks on the page, and we we run off then end of the
> - * current map or find the current map invalid, grab a new one.
> - * We only use bufferheads here to check per-block state - they no
> - * longer control the iteration through the page. This allows us to
> - * replace the bufferhead with some other state tracking mechanism in
> - * future.
> + * Walk through the page to find areas to write back. If we run off the
> + * end of the current map or find the current map invalid, grab a new
> + * one.
> */
> - for (poffset = 0, file_offset = page_offset(page);
> - poffset < PAGE_SIZE;
> - poffset += len, file_offset += len) {
> - /* past the range we are writing, so nothing more to write. */
> - if (file_offset >= end_offset)
> - break;
> -
> + for (i = 0, file_offset = page_offset(page);
> + i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
> + i++, file_offset += len) {
> /*
> * Block does not contain valid data, skip it.
> */
> - if (bh && !buffer_uptodate(bh)) {
> - if (PageUptodate(page))
> - ASSERT(buffer_mapped(bh));
> - bh = bh->b_this_page;
> + if (iop && !test_bit(i, iop->uptodate))
> continue;
> - }
>
> /*
> * If we don't have a valid map, now it's time to get a new one
> @@ -854,52 +693,33 @@ xfs_writepage_map(
> error = xfs_map_blocks(inode, file_offset, &wpc->imap,
> &wpc->io_type);
> if (error)
> - goto out;
> + break;
> }
>
> - if (wpc->io_type == XFS_IO_HOLE) {
> - /*
> - * set_page_dirty dirties all buffers in a page,
> independent
> - * of their state. The dirty state however is entirely
> - * meaningless for holes (!mapped && uptodate), so
> check we did
> - * have a buffer covering a hole here and continue.
> - */
> - if (bh)
> - bh = bh->b_this_page;
> - continue;
> - }
> -
> - if (bh) {
> - xfs_map_at_offset(inode, bh, &wpc->imap, file_offset);
> - bh = bh->b_this_page;
> + if (wpc->io_type != XFS_IO_HOLE) {
> + xfs_add_to_ioend(inode, file_offset, page, iop, wpc,
> + wbc, &submit_list);
> + count++;
> }
> - xfs_add_to_ioend(inode, file_offset, page, wpc, wbc,
> - &submit_list);
> - count++;
> }
>
> ASSERT(wpc->ioend || list_empty(&submit_list));
> -
> -out:
> ASSERT(PageLocked(page));
> ASSERT(!PageWriteback(page));
>
> /*
> - * On error, we have to fail the ioend here because we have locked
> - * buffers in the ioend. If we don't do this, we'll deadlock
> - * invalidating the page as that tries to lock the buffers on the page.
> - * Also, because we may have set pages under writeback, we have to make
> - * sure we run IO completion to mark the error state of the IO
> - * appropriately, so we can't cancel the ioend directly here. That means
> - * we have to mark this page as under writeback if we included any
> - * buffers from it in the ioend chain so that completion treats it
> - * correctly.
> + * On error, we have to fail the ioend here because we may have set
> + * pages under writeback, we have to make sure we run IO completion to
> + * mark the error state of the IO appropriately, so we can't cancel the
> + * ioend directly here. That means we have to mark this page as under
> + * writeback if we included any blocks from it in the ioend chain so
> + * that completion treats it correctly.
> *
> * If we didn't include the page in the ioend, the on error we can
> * simply discard and unlock it as there are no other users of the page
> - * or it's buffers right now. The caller will still need to trigger
> - * submission of outstanding ioends on the writepage context so they are
> - * treated correctly on error.
> + * now. The caller will still need to trigger submission of outstanding
> + * ioends on the writepage context so they are treated correctly on
> + * error.
> */
> if (unlikely(error)) {
> if (!count) {
> @@ -940,8 +760,8 @@ xfs_writepage_map(
> }
>
> /*
> - * We can end up here with no error and nothing to write if we race with
> - * a partial page truncate on a sub-page block sized filesystem.
> + * We can end up here with no error and nothing to write only if we race
> + * with a partial page truncate on a sub-page block sized filesystem.
> */
> if (!count)
> end_page_writeback(page);
> @@ -956,7 +776,6 @@ xfs_writepage_map(
> * For delalloc space on the page we need to allocate space and flush it.
> * For unwritten space on the page we need to start the conversion to
> * regular allocated space.
> - * For any other dirty buffer heads on the page we should flush them.
> */
> STATIC int
> xfs_do_writepage(
> @@ -1110,168 +929,6 @@ xfs_dax_writepages(
> xfs_find_bdev_for_inode(mapping->host), wbc);
> }
>
> -/*
> - * Called to move a page into cleanable state - and from there
> - * to be released. The page should already be clean. We always
> - * have buffer heads in this call.
> - *
> - * Returns 1 if the page is ok to release, 0 otherwise.
> - */
> -STATIC int
> -xfs_vm_releasepage(
> - struct page *page,
> - gfp_t gfp_mask)
> -{
> - int delalloc, unwritten;
> -
> - trace_xfs_releasepage(page->mapping->host, page, 0, 0);
> -
> - /*
> - * mm accommodates an old ext3 case where clean pages might not have had
> - * the dirty bit cleared. Thus, it can send actual dirty pages to
> - * ->releasepage() via shrink_active_list(). Conversely,
> - * block_invalidatepage() can send pages that are still marked dirty but
> - * otherwise have invalidated buffers.
> - *
> - * We want to release the latter to avoid unnecessary buildup of the
> - * LRU, so xfs_vm_invalidatepage() clears the page dirty flag on pages
> - * that are entirely invalidated and need to be released. Hence the
> - * only time we should get dirty pages here is through
> - * shrink_active_list() and so we can simply skip those now.
> - *
> - * warn if we've left any lingering delalloc/unwritten buffers on clean
> - * or invalidated pages we are about to release.
> - */
> - if (PageDirty(page))
> - return 0;
> -
> - xfs_count_page_state(page, &delalloc, &unwritten);
> -
> - if (WARN_ON_ONCE(delalloc))
> - return 0;
> - if (WARN_ON_ONCE(unwritten))
> - return 0;
> -
> - return try_to_free_buffers(page);
> -}
> -
> -/*
> - * If this is O_DIRECT or the mpage code calling tell them how large the
> mapping
> - * is, so that we can avoid repeated get_blocks calls.
> - *
> - * If the mapping spans EOF, then we have to break the mapping up as the
> mapping
> - * for blocks beyond EOF must be marked new so that sub block regions can be
> - * correctly zeroed. We can't do this for mappings within EOF unless the
> mapping
> - * was just allocated or is unwritten, otherwise the callers would overwrite
> - * existing data with zeros. Hence we have to split the mapping into a range
> up
> - * to and including EOF, and a second mapping for beyond EOF.
> - */
> -static void
> -xfs_map_trim_size(
> - struct inode *inode,
> - sector_t iblock,
> - struct buffer_head *bh_result,
> - struct xfs_bmbt_irec *imap,
> - xfs_off_t offset,
> - ssize_t size)
> -{
> - xfs_off_t mapping_size;
> -
> - mapping_size = imap->br_startoff + imap->br_blockcount - iblock;
> - mapping_size <<= inode->i_blkbits;
> -
> - ASSERT(mapping_size > 0);
> - if (mapping_size > size)
> - mapping_size = size;
> - if (offset < i_size_read(inode) &&
> - (xfs_ufsize_t)offset + mapping_size >= i_size_read(inode)) {
> - /* limit mapping to block that spans EOF */
> - mapping_size = roundup_64(i_size_read(inode) - offset,
> - i_blocksize(inode));
> - }
> - if (mapping_size > LONG_MAX)
> - mapping_size = LONG_MAX;
> -
> - bh_result->b_size = mapping_size;
> -}
> -
> -static int
> -xfs_get_blocks(
> - struct inode *inode,
> - sector_t iblock,
> - struct buffer_head *bh_result,
> - int create)
> -{
> - struct xfs_inode *ip = XFS_I(inode);
> - struct xfs_mount *mp = ip->i_mount;
> - xfs_fileoff_t offset_fsb, end_fsb;
> - int error = 0;
> - int lockmode = 0;
> - struct xfs_bmbt_irec imap;
> - int nimaps = 1;
> - xfs_off_t offset;
> - ssize_t size;
> -
> - BUG_ON(create);
> -
> - if (XFS_FORCED_SHUTDOWN(mp))
> - return -EIO;
> -
> - offset = (xfs_off_t)iblock << inode->i_blkbits;
> - ASSERT(bh_result->b_size >= i_blocksize(inode));
> - size = bh_result->b_size;
> -
> - if (offset >= i_size_read(inode))
> - return 0;
> -
> - /*
> - * Direct I/O is usually done on preallocated files, so try getting
> - * a block mapping without an exclusive lock first.
> - */
> - lockmode = xfs_ilock_data_map_shared(ip);
> -
> - ASSERT(offset <= mp->m_super->s_maxbytes);
> - if (offset > mp->m_super->s_maxbytes - size)
> - size = mp->m_super->s_maxbytes - offset;
> - end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
> - offset_fsb = XFS_B_TO_FSBT(mp, offset);
> -
> - error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
> - &nimaps, 0);
> - if (error)
> - goto out_unlock;
> - if (!nimaps) {
> - trace_xfs_get_blocks_notfound(ip, offset, size);
> - goto out_unlock;
> - }
> -
> - trace_xfs_get_blocks_found(ip, offset, size,
> - imap.br_state == XFS_EXT_UNWRITTEN ?
> - XFS_IO_UNWRITTEN : XFS_IO_OVERWRITE, &imap);
> - xfs_iunlock(ip, lockmode);
> -
> - /* trim mapping down to size requested */
> - xfs_map_trim_size(inode, iblock, bh_result, &imap, offset, size);
> -
> - /*
> - * For unwritten extents do not report a disk address in the buffered
> - * read case (treat as if we're reading into a hole).
> - */
> - if (xfs_bmap_is_real_extent(&imap))
> - xfs_map_buffer(inode, bh_result, &imap, offset);
> -
> - /*
> - * If this is a realtime file, data may be on a different device.
> - * to that pointed to from the buffer_head b_bdev currently.
> - */
> - bh_result->b_bdev = xfs_find_bdev_for_inode(inode);
> - return 0;
> -
> -out_unlock:
> - xfs_iunlock(ip, lockmode);
> - return error;
> -}
> -
> STATIC sector_t
> xfs_vm_bmap(
> struct address_space *mapping,
> @@ -1301,9 +958,7 @@ xfs_vm_readpage(
> struct page *page)
> {
> trace_xfs_vm_readpage(page->mapping->host, 1);
> - if (i_blocksize(page->mapping->host) == PAGE_SIZE)
> - return iomap_readpage(page, &xfs_iomap_ops);
> - return mpage_readpage(page, xfs_get_blocks);
> + return iomap_readpage(page, &xfs_iomap_ops);
> }
>
> STATIC int
> @@ -1314,65 +969,26 @@ xfs_vm_readpages(
> unsigned nr_pages)
> {
> trace_xfs_vm_readpages(mapping->host, nr_pages);
> - if (i_blocksize(mapping->host) == PAGE_SIZE)
> - return iomap_readpages(mapping, pages, nr_pages,
> &xfs_iomap_ops);
> - return mpage_readpages(mapping, pages, nr_pages, xfs_get_blocks);
> + return iomap_readpages(mapping, pages, nr_pages, &xfs_iomap_ops);
> }
>
> -/*
> - * This is basically a copy of __set_page_dirty_buffers() with one
> - * small tweak: buffers beyond EOF do not get marked dirty. If we mark them
> - * dirty, we'll never be able to clean them because we don't write buffers
> - * beyond EOF, and that means we can't invalidate pages that span EOF
> - * that have been marked dirty. Further, the dirty state can leak into
> - * the file interior if the file is extended, resulting in all sorts of
> - * bad things happening as the state does not match the underlying data.
> - *
> - * XXX: this really indicates that bufferheads in XFS need to die. Warts like
> - * this only exist because of bufferheads and how the generic code manages
> them.
> - */
> -STATIC int
> -xfs_vm_set_page_dirty(
> - struct page *page)
> +static int
> +xfs_vm_releasepage(
> + struct page *page,
> + gfp_t gfp_mask)
> {
> - struct address_space *mapping = page->mapping;
> - struct inode *inode = mapping->host;
> - loff_t end_offset;
> - loff_t offset;
> - int newly_dirty;
> -
> - if (unlikely(!mapping))
> - return !TestSetPageDirty(page);
> -
> - end_offset = i_size_read(inode);
> - offset = page_offset(page);
> -
> - spin_lock(&mapping->private_lock);
> - if (page_has_buffers(page)) {
> - struct buffer_head *head = page_buffers(page);
> - struct buffer_head *bh = head;
> + trace_xfs_releasepage(page->mapping->host, page, 0, 0);
> + return iomap_releasepage(page, gfp_mask);
> +}
>
> - do {
> - if (offset < end_offset)
> - set_buffer_dirty(bh);
> - bh = bh->b_this_page;
> - offset += i_blocksize(inode);
> - } while (bh != head);
> - }
> - /*
> - * Lock out page->mem_cgroup migration to keep PageDirty
> - * synchronized with per-memcg dirty page counters.
> - */
> - lock_page_memcg(page);
> - newly_dirty = !TestSetPageDirty(page);
> - spin_unlock(&mapping->private_lock);
> -
> - if (newly_dirty)
> - __set_page_dirty(page, mapping, 1);
> - unlock_page_memcg(page);
> - if (newly_dirty)
> - __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
> - return newly_dirty;
> +static void
> +xfs_vm_invalidatepage(
> + struct page *page,
> + unsigned int offset,
> + unsigned int length)
> +{
> + trace_xfs_invalidatepage(page->mapping->host, page, offset, length);
> + iomap_invalidatepage(page, offset, length);
> }
>
> static int
> @@ -1390,13 +1006,13 @@ const struct address_space_operations
> xfs_address_space_operations = {
> .readpages = xfs_vm_readpages,
> .writepage = xfs_vm_writepage,
> .writepages = xfs_vm_writepages,
> - .set_page_dirty = xfs_vm_set_page_dirty,
> + .set_page_dirty = iomap_set_page_dirty,
> .releasepage = xfs_vm_releasepage,
> .invalidatepage = xfs_vm_invalidatepage,
> .bmap = xfs_vm_bmap,
> .direct_IO = noop_direct_IO,
> - .migratepage = buffer_migrate_page,
> - .is_partially_uptodate = block_is_partially_uptodate,
> + .migratepage = iomap_migrate_page,
> + .is_partially_uptodate = iomap_is_partially_uptodate,
> .error_remove_page = generic_error_remove_page,
> .swap_activate = xfs_iomap_swapfile_activate,
> };
> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
> index f5f2b71c2fde..f3fa197bd272 100644
> --- a/fs/xfs/xfs_buf.h
> +++ b/fs/xfs/xfs_buf.h
> @@ -24,7 +24,6 @@
> #include <linux/mm.h>
> #include <linux/fs.h>
> #include <linux/dax.h>
> -#include <linux/buffer_head.h>
> #include <linux/uio.h>
> #include <linux/list_lru.h>
>
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 93c40da3378a..c646d84cd55e 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1031,9 +1031,6 @@ xfs_file_iomap_begin(
> if (XFS_FORCED_SHUTDOWN(mp))
> return -EIO;
>
> - if (i_blocksize(inode) < PAGE_SIZE)
> - iomap->flags |= IOMAP_F_BUFFER_HEAD;
> -
> if (((flags & (IOMAP_WRITE | IOMAP_DIRECT)) == IOMAP_WRITE) &&
> !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) {
> /* Reserve delalloc blocks for regular writeback. */
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 39e5ec3d407f..a9f23ec95216 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1866,7 +1866,7 @@ MODULE_ALIAS_FS("xfs");
> STATIC int __init
> xfs_init_zones(void)
> {
> - xfs_ioend_bioset = bioset_create(4 * MAX_BUF_PER_PAGE,
> + xfs_ioend_bioset = bioset_create(4 * (PAGE_SIZE / SECTOR_SIZE),
> offsetof(struct xfs_ioend, io_inline_bio),
> BIOSET_NEED_BVECS);
> if (!xfs_ioend_bioset)
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index ed8f774944ba..e4dc7c7f3da9 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -1165,33 +1165,23 @@ DECLARE_EVENT_CLASS(xfs_page_class,
> __field(loff_t, size)
> __field(unsigned long, offset)
> __field(unsigned int, length)
> - __field(int, delalloc)
> - __field(int, unwritten)
> ),
> TP_fast_assign(
> - int delalloc = -1, unwritten = -1;
> -
> - if (page_has_buffers(page))
> - xfs_count_page_state(page, &delalloc, &unwritten);
> __entry->dev = inode->i_sb->s_dev;
> __entry->ino = XFS_I(inode)->i_ino;
> __entry->pgoff = page_offset(page);
> __entry->size = i_size_read(inode);
> __entry->offset = off;
> __entry->length = len;
> - __entry->delalloc = delalloc;
> - __entry->unwritten = unwritten;
> ),
> TP_printk("dev %d:%d ino 0x%llx pgoff 0x%lx size 0x%llx offset %lx "
> - "length %x delalloc %d unwritten %d",
> + "length %x",
> MAJOR(__entry->dev), MINOR(__entry->dev),
> __entry->ino,
> __entry->pgoff,
> __entry->size,
> __entry->offset,
> - __entry->length,
> - __entry->delalloc,
> - __entry->unwritten)
> + __entry->length)
> )
>
> #define DEFINE_PAGE_EVENT(name) \
> @@ -1275,9 +1265,6 @@ DEFINE_EVENT(xfs_imap_class, name, \
> TP_ARGS(ip, offset, count, type, irec))
> DEFINE_IOMAP_EVENT(xfs_map_blocks_found);
> DEFINE_IOMAP_EVENT(xfs_map_blocks_alloc);
> -DEFINE_IOMAP_EVENT(xfs_get_blocks_found);
> -DEFINE_IOMAP_EVENT(xfs_get_blocks_alloc);
> -DEFINE_IOMAP_EVENT(xfs_get_blocks_map_direct);
> DEFINE_IOMAP_EVENT(xfs_iomap_alloc);
> DEFINE_IOMAP_EVENT(xfs_iomap_found);
>
> @@ -1316,7 +1303,6 @@ DEFINE_EVENT(xfs_simple_io_class, name, \
> TP_ARGS(ip, offset, count))
> DEFINE_SIMPLE_IO_EVENT(xfs_delalloc_enospc);
> DEFINE_SIMPLE_IO_EVENT(xfs_unwritten_convert);
> -DEFINE_SIMPLE_IO_EVENT(xfs_get_blocks_notfound);
> DEFINE_SIMPLE_IO_EVENT(xfs_setfilesize);
> DEFINE_SIMPLE_IO_EVENT(xfs_zero_eof);
> DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write);
> --
> 2.17.0
>
> --
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