1 files changed, 584 insertions, 0 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
new file mode 100644
index 000000000..5d1a995b1
--- /dev/null
+++ b/fs/xfs/xfs_aops.c
@@ -0,0 +1,584 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2016-2018 Christoph Hellwig.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_iomap.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_reflink.h"
+
+struct xfs_writepage_ctx {
+	struct iomap_writepage_ctx ctx;
+	unsigned int		data_seq;
+	unsigned int		cow_seq;
+};
+
+static inline struct xfs_writepage_ctx *
+XFS_WPC(struct iomap_writepage_ctx *ctx)
+{
+	return container_of(ctx, struct xfs_writepage_ctx, ctx);
+}
+
+/*
+ * Fast and loose check if this write could update the on-disk inode size.
+ */
+static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend)
+{
+	return ioend->io_offset + ioend->io_size >
+		XFS_I(ioend->io_inode)->i_disk_size;
+}
+
+/*
+ * Update on-disk file size now that data has been written to disk.
+ */
+int
+xfs_setfilesize(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	size_t			size)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_trans	*tp;
+	xfs_fsize_t		isize;
+	int			error;
+
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
+	if (error)
+		return error;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	isize = xfs_new_eof(ip, offset + size);
+	if (!isize) {
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		xfs_trans_cancel(tp);
+		return 0;
+	}
+
+	trace_xfs_setfilesize(ip, offset, size);
+
+	ip->i_disk_size = isize;
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+	return xfs_trans_commit(tp);
+}
+
+/*
+ * IO write completion.
+ */
+STATIC void
+xfs_end_ioend(
+	struct iomap_ioend	*ioend)
+{
+	struct xfs_inode	*ip = XFS_I(ioend->io_inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_off_t		offset = ioend->io_offset;
+	size_t			size = ioend->io_size;
+	unsigned int		nofs_flag;
+	int			error;
+
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+
+	/*
+	 * Just clean up the in-memory structures if the fs has been shut down.
+	 */
+	if (xfs_is_shutdown(mp)) {
+		error = -EIO;
+		goto done;
+	}
+
+	/*
+	 * Clean up all COW blocks and underlying data fork delalloc blocks on
+	 * I/O error. The delalloc punch is required because this ioend was
+	 * mapped to blocks in the COW fork and the associated pages are no
+	 * longer dirty. If we don't remove delalloc blocks here, they become
+	 * stale and can corrupt free space accounting on unmount.
+	 */
+	error = blk_status_to_errno(ioend->io_bio->bi_status);
+	if (unlikely(error)) {
+		if (ioend->io_flags & IOMAP_F_SHARED) {
+			xfs_reflink_cancel_cow_range(ip, offset, size, true);
+			xfs_bmap_punch_delalloc_range(ip,
+						      XFS_B_TO_FSBT(mp, offset),
+						      XFS_B_TO_FSB(mp, size));
+		}
+		goto done;
+	}
+
+	/*
+	 * Success: commit the COW or unwritten blocks if needed.
+	 */
+	if (ioend->io_flags & IOMAP_F_SHARED)
+		error = xfs_reflink_end_cow(ip, offset, size);
+	else if (ioend->io_type == IOMAP_UNWRITTEN)
+		error = xfs_iomap_write_unwritten(ip, offset, size, false);
+
+	if (!error && xfs_ioend_is_append(ioend))
+		error = xfs_setfilesize(ip, ioend->io_offset, ioend->io_size);
+done:
+	iomap_finish_ioends(ioend, error);
+	memalloc_nofs_restore(nofs_flag);
+}
+
+/*
+ * Finish all pending IO completions that require transactional modifications.
+ *
+ * We try to merge physical and logically contiguous ioends before completion to
+ * minimise the number of transactions we need to perform during IO completion.
+ * Both unwritten extent conversion and COW remapping need to iterate and modify
+ * one physical extent at a time, so we gain nothing by merging physically
+ * discontiguous extents here.
+ *
+ * The ioend chain length that we can be processing here is largely unbound in
+ * length and we may have to perform significant amounts of work on each ioend
+ * to complete it. Hence we have to be careful about holding the CPU for too
+ * long in this loop.
+ */
+void
+xfs_end_io(
+	struct work_struct	*work)
+{
+	struct xfs_inode	*ip =
+		container_of(work, struct xfs_inode, i_ioend_work);
+	struct iomap_ioend	*ioend;
+	struct list_head	tmp;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&ip->i_ioend_lock, flags);
+	list_replace_init(&ip->i_ioend_list, &tmp);
+	spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
+
+	iomap_sort_ioends(&tmp);
+	while ((ioend = list_first_entry_or_null(&tmp, struct iomap_ioend,
+			io_list))) {
+		list_del_init(&ioend->io_list);
+		iomap_ioend_try_merge(ioend, &tmp);
+		xfs_end_ioend(ioend);
+		cond_resched();
+	}
+}
+
+STATIC void
+xfs_end_bio(
+	struct bio		*bio)
+{
+	struct iomap_ioend	*ioend = bio->bi_private;
+	struct xfs_inode	*ip = XFS_I(ioend->io_inode);
+	unsigned long		flags;
+
+	spin_lock_irqsave(&ip->i_ioend_lock, flags);
+	if (list_empty(&ip->i_ioend_list))
+		WARN_ON_ONCE(!queue_work(ip->i_mount->m_unwritten_workqueue,
+					 &ip->i_ioend_work));
+	list_add_tail(&ioend->io_list, &ip->i_ioend_list);
+	spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
+}
+
+/*
+ * Fast revalidation of the cached writeback mapping. Return true if the current
+ * mapping is valid, false otherwise.
+ */
+static bool
+xfs_imap_valid(
+	struct iomap_writepage_ctx	*wpc,
+	struct xfs_inode		*ip,
+	loff_t				offset)
+{
+	if (offset < wpc->iomap.offset ||
+	    offset >= wpc->iomap.offset + wpc->iomap.length)
+		return false;
+	/*
+	 * If this is a COW mapping, it is sufficient to check that the mapping
+	 * covers the offset. Be careful to check this first because the caller
+	 * can revalidate a COW mapping without updating the data seqno.
+	 */
+	if (wpc->iomap.flags & IOMAP_F_SHARED)
+		return true;
+
+	/*
+	 * This is not a COW mapping. Check the sequence number of the data fork
+	 * because concurrent changes could have invalidated the extent. Check
+	 * the COW fork because concurrent changes since the last time we
+	 * checked (and found nothing at this offset) could have added
+	 * overlapping blocks.
+	 */
+	if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq))
+		return false;
+	if (xfs_inode_has_cow_data(ip) &&
+	    XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq))
+		return false;
+	return true;
+}
+
+/*
+ * Pass in a dellalloc extent and convert it to real extents, return the real
+ * extent that maps offset_fsb in wpc->iomap.
+ *
+ * The current page is held locked so nothing could have removed the block
+ * backing offset_fsb, although it could have moved from the COW to the data
+ * fork by another thread.
+ */
+static int
+xfs_convert_blocks(
+	struct iomap_writepage_ctx *wpc,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	loff_t			offset)
+{
+	int			error;
+	unsigned		*seq;
+
+	if (whichfork == XFS_COW_FORK)
+		seq = &XFS_WPC(wpc)->cow_seq;
+	else
+		seq = &XFS_WPC(wpc)->data_seq;
+
+	/*
+	 * Attempt to allocate whatever delalloc extent currently backs offset
+	 * and put the result into wpc->iomap.  Allocate in a loop because it
+	 * may take several attempts to allocate real blocks for a contiguous
+	 * delalloc extent if free space is sufficiently fragmented.
+	 */
+	do {
+		error = xfs_bmapi_convert_delalloc(ip, whichfork, offset,
+				&wpc->iomap, seq);
+		if (error)
+			return error;
+	} while (wpc->iomap.offset + wpc->iomap.length <= offset);
+
+	return 0;
+}
+
+static int
+xfs_map_blocks(
+	struct iomap_writepage_ctx *wpc,
+	struct inode		*inode,
+	loff_t			offset)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	ssize_t			count = i_blocksize(inode);
+	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
+	xfs_fileoff_t		cow_fsb;
+	int			whichfork;
+	struct xfs_bmbt_irec	imap;
+	struct xfs_iext_cursor	icur;
+	int			retries = 0;
+	int			error = 0;
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	/*
+	 * COW fork blocks can overlap data fork blocks even if the blocks
+	 * aren't shared.  COW I/O always takes precedent, so we must always
+	 * check for overlap on reflink inodes unless the mapping is already a
+	 * COW one, or the COW fork hasn't changed from the last time we looked
+	 * at it.
+	 *
+	 * It's safe to check the COW fork if_seq here without the ILOCK because
+	 * we've indirectly protected against concurrent updates: writeback has
+	 * the page locked, which prevents concurrent invalidations by reflink
+	 * and directio and prevents concurrent buffered writes to the same
+	 * page.  Changes to if_seq always happen under i_lock, which protects
+	 * against concurrent updates and provides a memory barrier on the way
+	 * out that ensures that we always see the current value.
+	 */
+	if (xfs_imap_valid(wpc, ip, offset))
+		return 0;
+
+	/*
+	 * If we don't have a valid map, now it's time to get a new one for this
+	 * offset.  This will convert delayed allocations (including COW ones)
+	 * into real extents.  If we return without a valid map, it means we
+	 * landed in a hole and we skip the block.
+	 */
+retry:
+	cow_fsb = NULLFILEOFF;
+	whichfork = XFS_DATA_FORK;
+	xfs_ilock(ip, XFS_ILOCK_SHARED);
+	ASSERT(!xfs_need_iread_extents(&ip->i_df));
+
+	/*
+	 * Check if this is offset is covered by a COW extents, and if yes use
+	 * it directly instead of looking up anything in the data fork.
+	 */
+	if (xfs_inode_has_cow_data(ip) &&
+	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap))
+		cow_fsb = imap.br_startoff;
+	if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
+		XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
+		xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+		whichfork = XFS_COW_FORK;
+		goto allocate_blocks;
+	}
+
+	/*
+	 * No COW extent overlap. Revalidate now that we may have updated
+	 * ->cow_seq. If the data mapping is still valid, we're done.
+	 */
+	if (xfs_imap_valid(wpc, ip, offset)) {
+		xfs_iunlock(ip, XFS_ILOCK_SHARED);
+		return 0;
+	}
+
+	/*
+	 * If we don't have a valid map, now it's time to get a new one for this
+	 * offset.  This will convert delayed allocations (including COW ones)
+	 * into real extents.
+	 */
+	if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap))
+		imap.br_startoff = end_fsb;	/* fake a hole past EOF */
+	XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq);
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+	/* landed in a hole or beyond EOF? */
+	if (imap.br_startoff > offset_fsb) {
+		imap.br_blockcount = imap.br_startoff - offset_fsb;
+		imap.br_startoff = offset_fsb;
+		imap.br_startblock = HOLESTARTBLOCK;
+		imap.br_state = XFS_EXT_NORM;
+	}
+
+	/*
+	 * Truncate to the next COW extent if there is one.  This is the only
+	 * opportunity to do this because we can skip COW fork lookups for the
+	 * subsequent blocks in the mapping; however, the requirement to treat
+	 * the COW range separately remains.
+	 */
+	if (cow_fsb != NULLFILEOFF &&
+	    cow_fsb < imap.br_startoff + imap.br_blockcount)
+		imap.br_blockcount = cow_fsb - imap.br_startoff;
+
+	/* got a delalloc extent? */
+	if (imap.br_startblock != HOLESTARTBLOCK &&
+	    isnullstartblock(imap.br_startblock))
+		goto allocate_blocks;
+
+	xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0, 0);
+	trace_xfs_map_blocks_found(ip, offset, count, whichfork, &imap);
+	return 0;
+allocate_blocks:
+	error = xfs_convert_blocks(wpc, ip, whichfork, offset);
+	if (error) {
+		/*
+		 * If we failed to find the extent in the COW fork we might have
+		 * raced with a COW to data fork conversion or truncate.
+		 * Restart the lookup to catch the extent in the data fork for
+		 * the former case, but prevent additional retries to avoid
+		 * looping forever for the latter case.
+		 */
+		if (error == -EAGAIN && whichfork == XFS_COW_FORK && !retries++)
+			goto retry;
+		ASSERT(error != -EAGAIN);
+		return error;
+	}
+
+	/*
+	 * Due to merging the return real extent might be larger than the
+	 * original delalloc one.  Trim the return extent to the next COW
+	 * boundary again to force a re-lookup.
+	 */
+	if (whichfork != XFS_COW_FORK && cow_fsb != NULLFILEOFF) {
+		loff_t		cow_offset = XFS_FSB_TO_B(mp, cow_fsb);
+
+		if (cow_offset < wpc->iomap.offset + wpc->iomap.length)
+			wpc->iomap.length = cow_offset - wpc->iomap.offset;
+	}
+
+	ASSERT(wpc->iomap.offset <= offset);
+	ASSERT(wpc->iomap.offset + wpc->iomap.length > offset);
+	trace_xfs_map_blocks_alloc(ip, offset, count, whichfork, &imap);
+	return 0;
+}
+
+static int
+xfs_prepare_ioend(
+	struct iomap_ioend	*ioend,
+	int			status)
+{
+	unsigned int		nofs_flag;
+
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+
+	/* Convert CoW extents to regular */
+	if (!status && (ioend->io_flags & IOMAP_F_SHARED)) {
+		status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
+				ioend->io_offset, ioend->io_size);
+	}
+
+	memalloc_nofs_restore(nofs_flag);
+
+	/* send ioends that might require a transaction to the completion wq */
+	if (xfs_ioend_is_append(ioend) || ioend->io_type == IOMAP_UNWRITTEN ||
+	    (ioend->io_flags & IOMAP_F_SHARED))
+		ioend->io_bio->bi_end_io = xfs_end_bio;
+	return status;
+}
+
+/*
+ * If the page has delalloc blocks on it, we need to punch them out before we
+ * invalidate the page.  If we don't, we leave a stale delalloc mapping on the
+ * inode that can trip up a later direct I/O read operation on the same region.
+ *
+ * We prevent this by truncating away the delalloc regions on the page.  Because
+ * they are delalloc, we can do this without needing a transaction. Indeed - if
+ * we get ENOSPC errors, we have to be able to do this truncation without a
+ * transaction as there is no space left for block reservation (typically why we
+ * see a ENOSPC in writeback).
+ */
+static void
+xfs_discard_folio(
+	struct folio		*folio,
+	loff_t			pos)
+{
+	struct inode		*inode = folio->mapping->host;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	size_t			offset = offset_in_folio(folio, pos);
+	xfs_fileoff_t		start_fsb = XFS_B_TO_FSBT(mp, pos);
+	xfs_fileoff_t		pageoff_fsb = XFS_B_TO_FSBT(mp, offset);
+	int			error;
+
+	if (xfs_is_shutdown(mp))
+		return;
+
+	xfs_alert_ratelimited(mp,
+		"page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
+			folio, ip->i_ino, pos);
+
+	error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
+			i_blocks_per_folio(inode, folio) - pageoff_fsb);
+	if (error && !xfs_is_shutdown(mp))
+		xfs_alert(mp, "page discard unable to remove delalloc mapping.");
+}
+
+static const struct iomap_writeback_ops xfs_writeback_ops = {
+	.map_blocks		= xfs_map_blocks,
+	.prepare_ioend		= xfs_prepare_ioend,
+	.discard_folio		= xfs_discard_folio,
+};
+
+STATIC int
+xfs_vm_writepages(
+	struct address_space	*mapping,
+	struct writeback_control *wbc)
+{
+	struct xfs_writepage_ctx wpc = { };
+
+	/*
+	 * Writing back data in a transaction context can result in recursive
+	 * transactions. This is bad, so issue a warning and get out of here.
+	 */
+	if (WARN_ON_ONCE(current->journal_info))
+		return 0;
+
+	xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+	return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops);
+}
+
+STATIC int
+xfs_dax_writepages(
+	struct address_space	*mapping,
+	struct writeback_control *wbc)
+{
+	struct xfs_inode	*ip = XFS_I(mapping->host);
+
+	xfs_iflags_clear(ip, XFS_ITRUNCATED);
+	return dax_writeback_mapping_range(mapping,
+			xfs_inode_buftarg(ip)->bt_daxdev, wbc);
+}
+
+STATIC sector_t
+xfs_vm_bmap(
+	struct address_space	*mapping,
+	sector_t		block)
+{
+	struct xfs_inode	*ip = XFS_I(mapping->host);
+
+	trace_xfs_vm_bmap(ip);
+
+	/*
+	 * The swap code (ab-)uses ->bmap to get a block mapping and then
+	 * bypasses the file system for actual I/O.  We really can't allow
+	 * that on reflinks inodes, so we have to skip out here.  And yes,
+	 * 0 is the magic code for a bmap error.
+	 *
+	 * Since we don't pass back blockdev info, we can't return bmap
+	 * information for rt files either.
+	 */
+	if (xfs_is_cow_inode(ip) || XFS_IS_REALTIME_INODE(ip))
+		return 0;
+	return iomap_bmap(mapping, block, &xfs_read_iomap_ops);
+}
+
+STATIC int
+xfs_vm_read_folio(
+	struct file		*unused,
+	struct folio		*folio)
+{
+	return iomap_read_folio(folio, &xfs_read_iomap_ops);
+}
+
+STATIC void
+xfs_vm_readahead(
+	struct readahead_control	*rac)
+{
+	iomap_readahead(rac, &xfs_read_iomap_ops);
+}
+
+static int
+xfs_iomap_swapfile_activate(
+	struct swap_info_struct		*sis,
+	struct file			*swap_file,
+	sector_t			*span)
+{
+	sis->bdev = xfs_inode_buftarg(XFS_I(file_inode(swap_file)))->bt_bdev;
+	return iomap_swapfile_activate(sis, swap_file, span,
+			&xfs_read_iomap_ops);
+}
+
+const struct address_space_operations xfs_address_space_operations = {
+	.read_folio		= xfs_vm_read_folio,
+	.readahead		= xfs_vm_readahead,
+	.writepages		= xfs_vm_writepages,
+	.dirty_folio		= filemap_dirty_folio,
+	.release_folio		= iomap_release_folio,
+	.invalidate_folio	= iomap_invalidate_folio,
+	.bmap			= xfs_vm_bmap,
+	.direct_IO		= noop_direct_IO,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate  = iomap_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+	.swap_activate		= xfs_iomap_swapfile_activate,
+};
+
+const struct address_space_operations xfs_dax_aops = {
+	.writepages		= xfs_dax_writepages,
+	.direct_IO		= noop_direct_IO,
+	.dirty_folio		= noop_dirty_folio,
+	.swap_activate		= xfs_iomap_swapfile_activate,
+};