v4.19.13 snapshot.
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
new file mode 100644
index 0000000..49f5f58
--- /dev/null
+++ b/fs/xfs/xfs_aops.c
@@ -0,0 +1,1041 @@
+// 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_inode_item.h"
+#include "xfs_alloc.h"
+#include "xfs_error.h"
+#include "xfs_iomap.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_reflink.h"
+#include <linux/writeback.h>
+
+/*
+ * structure owned by writepages passed to individual writepage calls
+ */
+struct xfs_writepage_ctx {
+ struct xfs_bmbt_irec imap;
+ unsigned int io_type;
+ unsigned int cow_seq;
+ struct xfs_ioend *ioend;
+};
+
+struct block_device *
+xfs_find_bdev_for_inode(
+ struct inode *inode)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+
+ if (XFS_IS_REALTIME_INODE(ip))
+ return mp->m_rtdev_targp->bt_bdev;
+ else
+ return mp->m_ddev_targp->bt_bdev;
+}
+
+struct dax_device *
+xfs_find_daxdev_for_inode(
+ struct inode *inode)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+
+ if (XFS_IS_REALTIME_INODE(ip))
+ return mp->m_rtdev_targp->bt_daxdev;
+ else
+ return mp->m_ddev_targp->bt_daxdev;
+}
+
+static void
+xfs_finish_page_writeback(
+ struct inode *inode,
+ struct bio_vec *bvec,
+ int error)
+{
+ struct iomap_page *iop = to_iomap_page(bvec->bv_page);
+
+ if (error) {
+ SetPageError(bvec->bv_page);
+ mapping_set_error(inode->i_mapping, -EIO);
+ }
+
+ ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
+ ASSERT(!iop || atomic_read(&iop->write_count) > 0);
+
+ if (!iop || atomic_dec_and_test(&iop->write_count))
+ end_page_writeback(bvec->bv_page);
+}
+
+/*
+ * We're now finished for good with this ioend structure. Update the page
+ * state, release holds on bios, and finally free up memory. Do not use the
+ * ioend after this.
+ */
+STATIC void
+xfs_destroy_ioend(
+ struct xfs_ioend *ioend,
+ int error)
+{
+ struct inode *inode = ioend->io_inode;
+ struct bio *bio = &ioend->io_inline_bio;
+ struct bio *last = ioend->io_bio, *next;
+ u64 start = bio->bi_iter.bi_sector;
+ bool quiet = bio_flagged(bio, BIO_QUIET);
+
+ for (bio = &ioend->io_inline_bio; bio; bio = next) {
+ struct bio_vec *bvec;
+ int i;
+
+ /*
+ * For the last bio, bi_private points to the ioend, so we
+ * need to explicitly end the iteration here.
+ */
+ if (bio == last)
+ next = NULL;
+ else
+ next = bio->bi_private;
+
+ /* walk each page on bio, ending page IO on them */
+ bio_for_each_segment_all(bvec, bio, i)
+ xfs_finish_page_writeback(inode, bvec, error);
+ bio_put(bio);
+ }
+
+ if (unlikely(error && !quiet)) {
+ xfs_err_ratelimited(XFS_I(inode)->i_mount,
+ "writeback error on sector %llu", start);
+ }
+}
+
+/*
+ * Fast and loose check if this write could update the on-disk inode size.
+ */
+static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
+{
+ return ioend->io_offset + ioend->io_size >
+ XFS_I(ioend->io_inode)->i_d.di_size;
+}
+
+STATIC int
+xfs_setfilesize_trans_alloc(
+ struct xfs_ioend *ioend)
+{
+ struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
+ struct xfs_trans *tp;
+ int error;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0,
+ XFS_TRANS_NOFS, &tp);
+ if (error)
+ return error;
+
+ ioend->io_append_trans = tp;
+
+ /*
+ * We may pass freeze protection with a transaction. So tell lockdep
+ * we released it.
+ */
+ __sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
+ /*
+ * We hand off the transaction to the completion thread now, so
+ * clear the flag here.
+ */
+ current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
+ return 0;
+}
+
+/*
+ * Update on-disk file size now that data has been written to disk.
+ */
+STATIC int
+__xfs_setfilesize(
+ struct xfs_inode *ip,
+ struct xfs_trans *tp,
+ xfs_off_t offset,
+ size_t size)
+{
+ xfs_fsize_t isize;
+
+ 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_d.di_size = isize;
+ xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+ return xfs_trans_commit(tp);
+}
+
+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;
+ int error;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
+ if (error)
+ return error;
+
+ return __xfs_setfilesize(ip, tp, offset, size);
+}
+
+STATIC int
+xfs_setfilesize_ioend(
+ struct xfs_ioend *ioend,
+ int error)
+{
+ struct xfs_inode *ip = XFS_I(ioend->io_inode);
+ struct xfs_trans *tp = ioend->io_append_trans;
+
+ /*
+ * The transaction may have been allocated in the I/O submission thread,
+ * thus we need to mark ourselves as being in a transaction manually.
+ * Similarly for freeze protection.
+ */
+ current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
+ __sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
+
+ /* we abort the update if there was an IO error */
+ if (error) {
+ xfs_trans_cancel(tp);
+ return error;
+ }
+
+ return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
+}
+
+/*
+ * IO write completion.
+ */
+STATIC void
+xfs_end_io(
+ struct work_struct *work)
+{
+ struct xfs_ioend *ioend =
+ container_of(work, struct xfs_ioend, io_work);
+ struct xfs_inode *ip = XFS_I(ioend->io_inode);
+ xfs_off_t offset = ioend->io_offset;
+ size_t size = ioend->io_size;
+ int error;
+
+ /*
+ * Just clean up the in-memory strutures if the fs has been shut down.
+ */
+ if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+ error = -EIO;
+ goto done;
+ }
+
+ /*
+ * Clean up any COW blocks on an I/O error.
+ */
+ error = blk_status_to_errno(ioend->io_bio->bi_status);
+ if (unlikely(error)) {
+ switch (ioend->io_type) {
+ case XFS_IO_COW:
+ xfs_reflink_cancel_cow_range(ip, offset, size, true);
+ break;
+ }
+
+ goto done;
+ }
+
+ /*
+ * Success: commit the COW or unwritten blocks if needed.
+ */
+ switch (ioend->io_type) {
+ case XFS_IO_COW:
+ error = xfs_reflink_end_cow(ip, offset, size);
+ break;
+ case XFS_IO_UNWRITTEN:
+ /* writeback should never update isize */
+ error = xfs_iomap_write_unwritten(ip, offset, size, false);
+ break;
+ default:
+ ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_append_trans);
+ break;
+ }
+
+done:
+ if (ioend->io_append_trans)
+ error = xfs_setfilesize_ioend(ioend, error);
+ xfs_destroy_ioend(ioend, error);
+}
+
+STATIC void
+xfs_end_bio(
+ struct bio *bio)
+{
+ struct xfs_ioend *ioend = bio->bi_private;
+ struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
+
+ if (ioend->io_type == XFS_IO_UNWRITTEN || ioend->io_type == XFS_IO_COW)
+ queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
+ else if (ioend->io_append_trans)
+ queue_work(mp->m_data_workqueue, &ioend->io_work);
+ else
+ xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status));
+}
+
+STATIC int
+xfs_map_blocks(
+ struct xfs_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), end_fsb;
+ xfs_fileoff_t cow_fsb = NULLFILEOFF;
+ struct xfs_bmbt_irec imap;
+ int whichfork = XFS_DATA_FORK;
+ struct xfs_iext_cursor icur;
+ bool imap_valid;
+ int error = 0;
+
+ /*
+ * We have to make sure the cached mapping is within EOF to protect
+ * against eofblocks trimming on file release leaving us with a stale
+ * mapping. Otherwise, a page for a subsequent file extending buffered
+ * write could get picked up by this writeback cycle and written to the
+ * wrong blocks.
+ *
+ * Note that what we really want here is a generic mapping invalidation
+ * mechanism to protect us from arbitrary extent modifying contexts, not
+ * just eofblocks.
+ */
+ xfs_trim_extent_eof(&wpc->imap, ip);
+
+ /*
+ * 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.
+ */
+ imap_valid = offset_fsb >= wpc->imap.br_startoff &&
+ offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount;
+ if (imap_valid &&
+ (!xfs_inode_has_cow_data(ip) ||
+ wpc->io_type == XFS_IO_COW ||
+ wpc->cow_seq == READ_ONCE(ip->i_cowfp->if_seq)))
+ return 0;
+
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
+ /*
+ * 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.
+ */
+ xfs_ilock(ip, XFS_ILOCK_SHARED);
+ ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
+ (ip->i_df.if_flags & XFS_IFEXTENTS));
+ ASSERT(offset <= mp->m_super->s_maxbytes);
+
+ if (offset > mp->m_super->s_maxbytes - count)
+ count = mp->m_super->s_maxbytes - offset;
+ end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
+
+ /*
+ * 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) {
+ wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
+ xfs_iunlock(ip, XFS_ILOCK_SHARED);
+ /*
+ * Truncate can race with writeback since writeback doesn't
+ * take the iolock and truncate decreases the file size before
+ * it starts truncating the pages between new_size and old_size.
+ * Therefore, we can end up in the situation where writeback
+ * gets a CoW fork mapping but the truncate makes the mapping
+ * invalid and we end up in here trying to get a new mapping.
+ * bail out here so that we simply never get a valid mapping
+ * and so we drop the write altogether. The page truncation
+ * will kill the contents anyway.
+ */
+ if (offset > i_size_read(inode)) {
+ wpc->io_type = XFS_IO_HOLE;
+ return 0;
+ }
+ whichfork = XFS_COW_FORK;
+ wpc->io_type = XFS_IO_COW;
+ goto allocate_blocks;
+ }
+
+ /*
+ * Map valid and no COW extent in the way? We're done.
+ */
+ if (imap_valid) {
+ 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_iunlock(ip, XFS_ILOCK_SHARED);
+
+ if (imap.br_startoff > offset_fsb) {
+ /* landed in a hole or beyond EOF */
+ imap.br_blockcount = imap.br_startoff - offset_fsb;
+ imap.br_startoff = offset_fsb;
+ imap.br_startblock = HOLESTARTBLOCK;
+ wpc->io_type = XFS_IO_HOLE;
+ } else {
+ /*
+ * 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;
+
+ if (isnullstartblock(imap.br_startblock)) {
+ /* got a delalloc extent */
+ wpc->io_type = XFS_IO_DELALLOC;
+ goto allocate_blocks;
+ }
+
+ if (imap.br_state == XFS_EXT_UNWRITTEN)
+ wpc->io_type = XFS_IO_UNWRITTEN;
+ else
+ wpc->io_type = XFS_IO_OVERWRITE;
+ }
+
+ wpc->imap = imap;
+ trace_xfs_map_blocks_found(ip, offset, count, wpc->io_type, &imap);
+ return 0;
+allocate_blocks:
+ error = xfs_iomap_write_allocate(ip, whichfork, offset, &imap,
+ &wpc->cow_seq);
+ if (error)
+ return error;
+ ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF ||
+ imap.br_startoff + imap.br_blockcount <= cow_fsb);
+ wpc->imap = imap;
+ trace_xfs_map_blocks_alloc(ip, offset, count, wpc->io_type, &imap);
+ return 0;
+}
+
+/*
+ * Submit the bio for an ioend. We are passed an ioend with a bio attached to
+ * it, and we submit that bio. The ioend may be used for multiple bio
+ * submissions, so we only want to allocate an append transaction for the ioend
+ * once. In the case of multiple bio submission, each bio will take an IO
+ * reference to the ioend to ensure that the ioend completion is only done once
+ * all bios have been submitted and the ioend is really done.
+ *
+ * If @fail is non-zero, it means that we have a situation where some part of
+ * the submission process has failed after we have marked paged for writeback
+ * and unlocked them. In this situation, we need to fail the bio and ioend
+ * rather than submit it to IO. This typically only happens on a filesystem
+ * shutdown.
+ */
+STATIC int
+xfs_submit_ioend(
+ struct writeback_control *wbc,
+ struct xfs_ioend *ioend,
+ int status)
+{
+ /* Convert CoW extents to regular */
+ if (!status && ioend->io_type == XFS_IO_COW) {
+ /*
+ * Yuk. This can do memory allocation, but is not a
+ * transactional operation so everything is done in GFP_KERNEL
+ * context. That can deadlock, because we hold pages in
+ * writeback state and GFP_KERNEL allocations can block on them.
+ * Hence we must operate in nofs conditions here.
+ */
+ unsigned nofs_flag;
+
+ nofs_flag = memalloc_nofs_save();
+ status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
+ ioend->io_offset, ioend->io_size);
+ memalloc_nofs_restore(nofs_flag);
+ }
+
+ /* Reserve log space if we might write beyond the on-disk inode size. */
+ if (!status &&
+ ioend->io_type != XFS_IO_UNWRITTEN &&
+ xfs_ioend_is_append(ioend) &&
+ !ioend->io_append_trans)
+ status = xfs_setfilesize_trans_alloc(ioend);
+
+ ioend->io_bio->bi_private = ioend;
+ ioend->io_bio->bi_end_io = xfs_end_bio;
+ ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
+
+ /*
+ * If we are failing the IO now, just mark the ioend with an
+ * error and finish it. This will run IO completion immediately
+ * as there is only one reference to the ioend at this point in
+ * time.
+ */
+ if (status) {
+ ioend->io_bio->bi_status = errno_to_blk_status(status);
+ bio_endio(ioend->io_bio);
+ return status;
+ }
+
+ ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
+ submit_bio(ioend->io_bio);
+ return 0;
+}
+
+static struct xfs_ioend *
+xfs_alloc_ioend(
+ struct inode *inode,
+ unsigned int type,
+ xfs_off_t offset,
+ struct block_device *bdev,
+ sector_t sector)
+{
+ struct xfs_ioend *ioend;
+ struct bio *bio;
+
+ bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &xfs_ioend_bioset);
+ bio_set_dev(bio, bdev);
+ bio->bi_iter.bi_sector = sector;
+
+ ioend = container_of(bio, struct xfs_ioend, io_inline_bio);
+ INIT_LIST_HEAD(&ioend->io_list);
+ ioend->io_type = type;
+ ioend->io_inode = inode;
+ ioend->io_size = 0;
+ ioend->io_offset = offset;
+ INIT_WORK(&ioend->io_work, xfs_end_io);
+ ioend->io_append_trans = NULL;
+ ioend->io_bio = bio;
+ return ioend;
+}
+
+/*
+ * Allocate a new bio, and chain the old bio to the new one.
+ *
+ * Note that we have to do perform the chaining in this unintuitive order
+ * so that the bi_private linkage is set up in the right direction for the
+ * traversal in xfs_destroy_ioend().
+ */
+static void
+xfs_chain_bio(
+ struct xfs_ioend *ioend,
+ struct writeback_control *wbc,
+ struct block_device *bdev,
+ sector_t sector)
+{
+ struct bio *new;
+
+ new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
+ bio_set_dev(new, bdev);
+ new->bi_iter.bi_sector = sector;
+ bio_chain(ioend->io_bio, new);
+ bio_get(ioend->io_bio); /* for xfs_destroy_ioend */
+ ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
+ ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
+ submit_bio(ioend->io_bio);
+ ioend->io_bio = new;
+}
+
+/*
+ * Test to see if we have an existing ioend structure that we could append to
+ * first, otherwise finish off the current ioend and start another.
+ */
+STATIC void
+xfs_add_to_ioend(
+ struct inode *inode,
+ xfs_off_t offset,
+ struct page *page,
+ struct iomap_page *iop,
+ struct xfs_writepage_ctx *wpc,
+ struct writeback_control *wbc,
+ struct list_head *iolist)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+ struct block_device *bdev = xfs_find_bdev_for_inode(inode);
+ unsigned len = i_blocksize(inode);
+ unsigned poff = offset & (PAGE_SIZE - 1);
+ sector_t sector;
+
+ sector = xfs_fsb_to_db(ip, wpc->imap.br_startblock) +
+ ((offset - XFS_FSB_TO_B(mp, wpc->imap.br_startoff)) >> 9);
+
+ if (!wpc->ioend || wpc->io_type != wpc->ioend->io_type ||
+ sector != bio_end_sector(wpc->ioend->io_bio) ||
+ offset != wpc->ioend->io_offset + wpc->ioend->io_size) {
+ if (wpc->ioend)
+ list_add(&wpc->ioend->io_list, iolist);
+ wpc->ioend = xfs_alloc_ioend(inode, wpc->io_type, offset,
+ bdev, sector);
+ }
+
+ if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff)) {
+ if (iop)
+ atomic_inc(&iop->write_count);
+ if (bio_full(wpc->ioend->io_bio))
+ xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
+ __bio_add_page(wpc->ioend->io_bio, page, len, poff);
+ }
+
+ wpc->ioend->io_size += len;
+}
+
+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);
+}
+
+/*
+ * 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_aops_discard_page(
+ struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+ loff_t offset = page_offset(page);
+ xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, offset);
+ int error;
+
+ if (XFS_FORCED_SHUTDOWN(mp))
+ goto out_invalidate;
+
+ xfs_alert(mp,
+ "page discard on page "PTR_FMT", inode 0x%llx, offset %llu.",
+ page, ip->i_ino, offset);
+
+ error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
+ 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);
+}
+
+/*
+ * 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 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.
+ *
+ * If a new ioend is created and cached, the old ioend is returned and queued
+ * locally for submission once the entire page is processed or an error has been
+ * detected. While ioends are submitted immediately after they are completed,
+ * batching optimisations are provided by higher level block plugging.
+ *
+ * At the end of a writeback pass, there will be a cached ioend remaining on the
+ * writepage context that the caller will need to submit.
+ */
+static int
+xfs_writepage_map(
+ struct xfs_writepage_ctx *wpc,
+ struct writeback_control *wbc,
+ struct inode *inode,
+ struct page *page,
+ 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;
+ uint64_t file_offset; /* file offset of page */
+ int error = 0, count = 0, i;
+
+ ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
+ ASSERT(!iop || atomic_read(&iop->write_count) == 0);
+
+ /*
+ * 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 (i = 0, file_offset = page_offset(page);
+ i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
+ i++, file_offset += len) {
+ if (iop && !test_bit(i, iop->uptodate))
+ continue;
+
+ error = xfs_map_blocks(wpc, inode, file_offset);
+ if (error)
+ break;
+ if (wpc->io_type == XFS_IO_HOLE)
+ continue;
+ xfs_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
+ &submit_list);
+ count++;
+ }
+
+ ASSERT(wpc->ioend || list_empty(&submit_list));
+ ASSERT(PageLocked(page));
+ ASSERT(!PageWriteback(page));
+
+ /*
+ * 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
+ * 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) {
+ xfs_aops_discard_page(page);
+ ClearPageUptodate(page);
+ unlock_page(page);
+ goto done;
+ }
+
+ /*
+ * If the page was not fully cleaned, we need to ensure that the
+ * higher layers come back to it correctly. That means we need
+ * to keep the page dirty, and for WB_SYNC_ALL writeback we need
+ * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed
+ * so another attempt to write this page in this writeback sweep
+ * will be made.
+ */
+ set_page_writeback_keepwrite(page);
+ } else {
+ clear_page_dirty_for_io(page);
+ set_page_writeback(page);
+ }
+
+ unlock_page(page);
+
+ /*
+ * Preserve the original error if there was one, otherwise catch
+ * submission errors here and propagate into subsequent ioend
+ * submissions.
+ */
+ list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
+ int error2;
+
+ list_del_init(&ioend->io_list);
+ error2 = xfs_submit_ioend(wbc, ioend, error);
+ if (error2 && !error)
+ error = error2;
+ }
+
+ /*
+ * 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);
+done:
+ mapping_set_error(page->mapping, error);
+ return error;
+}
+
+/*
+ * Write out a dirty page.
+ *
+ * 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.
+ */
+STATIC int
+xfs_do_writepage(
+ struct page *page,
+ struct writeback_control *wbc,
+ void *data)
+{
+ struct xfs_writepage_ctx *wpc = data;
+ struct inode *inode = page->mapping->host;
+ loff_t offset;
+ uint64_t end_offset;
+ pgoff_t end_index;
+
+ trace_xfs_writepage(inode, page, 0, 0);
+
+ /*
+ * Refuse to write the page out if we are called from reclaim context.
+ *
+ * This avoids stack overflows when called from deeply used stacks in
+ * random callers for direct reclaim or memcg reclaim. We explicitly
+ * allow reclaim from kswapd as the stack usage there is relatively low.
+ *
+ * This should never happen except in the case of a VM regression so
+ * warn about it.
+ */
+ if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
+ PF_MEMALLOC))
+ goto redirty;
+
+ /*
+ * Given that we do not allow direct reclaim to call us, we should
+ * never be called while in a filesystem transaction.
+ */
+ if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
+ goto redirty;
+
+ /*
+ * Is this page beyond the end of the file?
+ *
+ * The page index is less than the end_index, adjust the end_offset
+ * to the highest offset that this page should represent.
+ * -----------------------------------------------------
+ * | file mapping | <EOF> |
+ * -----------------------------------------------------
+ * | Page ... | Page N-2 | Page N-1 | Page N | |
+ * ^--------------------------------^----------|--------
+ * | desired writeback range | see else |
+ * ---------------------------------^------------------|
+ */
+ offset = i_size_read(inode);
+ end_index = offset >> PAGE_SHIFT;
+ if (page->index < end_index)
+ end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT;
+ else {
+ /*
+ * Check whether the page to write out is beyond or straddles
+ * i_size or not.
+ * -------------------------------------------------------
+ * | file mapping | <EOF> |
+ * -------------------------------------------------------
+ * | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
+ * ^--------------------------------^-----------|---------
+ * | | Straddles |
+ * ---------------------------------^-----------|--------|
+ */
+ unsigned offset_into_page = offset & (PAGE_SIZE - 1);
+
+ /*
+ * Skip the page if it is fully outside i_size, e.g. due to a
+ * truncate operation that is in progress. We must redirty the
+ * page so that reclaim stops reclaiming it. Otherwise
+ * xfs_vm_releasepage() is called on it and gets confused.
+ *
+ * Note that the end_index is unsigned long, it would overflow
+ * if the given offset is greater than 16TB on 32-bit system
+ * and if we do check the page is fully outside i_size or not
+ * via "if (page->index >= end_index + 1)" as "end_index + 1"
+ * will be evaluated to 0. Hence this page will be redirtied
+ * and be written out repeatedly which would result in an
+ * infinite loop, the user program that perform this operation
+ * will hang. Instead, we can verify this situation by checking
+ * if the page to write is totally beyond the i_size or if it's
+ * offset is just equal to the EOF.
+ */
+ if (page->index > end_index ||
+ (page->index == end_index && offset_into_page == 0))
+ goto redirty;
+
+ /*
+ * The page straddles i_size. It must be zeroed out on each
+ * and every writepage invocation because it may be mmapped.
+ * "A file is mapped in multiples of the page size. For a file
+ * that is not a multiple of the page size, the remaining
+ * memory is zeroed when mapped, and writes to that region are
+ * not written out to the file."
+ */
+ zero_user_segment(page, offset_into_page, PAGE_SIZE);
+
+ /* Adjust the end_offset to the end of file */
+ end_offset = offset;
+ }
+
+ return xfs_writepage_map(wpc, wbc, inode, page, end_offset);
+
+redirty:
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return 0;
+}
+
+STATIC int
+xfs_vm_writepage(
+ struct page *page,
+ struct writeback_control *wbc)
+{
+ struct xfs_writepage_ctx wpc = {
+ .io_type = XFS_IO_INVALID,
+ };
+ int ret;
+
+ ret = xfs_do_writepage(page, wbc, &wpc);
+ if (wpc.ioend)
+ ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
+ return ret;
+}
+
+STATIC int
+xfs_vm_writepages(
+ struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ struct xfs_writepage_ctx wpc = {
+ .io_type = XFS_IO_INVALID,
+ };
+ int ret;
+
+ xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+ ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc);
+ if (wpc.ioend)
+ ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
+ return ret;
+}
+
+STATIC int
+xfs_dax_writepages(
+ struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+ return dax_writeback_mapping_range(mapping,
+ xfs_find_bdev_for_inode(mapping->host), wbc);
+}
+
+STATIC int
+xfs_vm_releasepage(
+ struct page *page,
+ gfp_t gfp_mask)
+{
+ trace_xfs_releasepage(page->mapping->host, page, 0, 0);
+ return iomap_releasepage(page, gfp_mask);
+}
+
+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_reflink_inode(ip) || XFS_IS_REALTIME_INODE(ip))
+ return 0;
+ return iomap_bmap(mapping, block, &xfs_iomap_ops);
+}
+
+STATIC int
+xfs_vm_readpage(
+ struct file *unused,
+ struct page *page)
+{
+ trace_xfs_vm_readpage(page->mapping->host, 1);
+ return iomap_readpage(page, &xfs_iomap_ops);
+}
+
+STATIC int
+xfs_vm_readpages(
+ struct file *unused,
+ struct address_space *mapping,
+ struct list_head *pages,
+ unsigned nr_pages)
+{
+ trace_xfs_vm_readpages(mapping->host, nr_pages);
+ return iomap_readpages(mapping, pages, nr_pages, &xfs_iomap_ops);
+}
+
+static int
+xfs_iomap_swapfile_activate(
+ struct swap_info_struct *sis,
+ struct file *swap_file,
+ sector_t *span)
+{
+ sis->bdev = xfs_find_bdev_for_inode(file_inode(swap_file));
+ return iomap_swapfile_activate(sis, swap_file, span, &xfs_iomap_ops);
+}
+
+const struct address_space_operations xfs_address_space_operations = {
+ .readpage = xfs_vm_readpage,
+ .readpages = xfs_vm_readpages,
+ .writepage = xfs_vm_writepage,
+ .writepages = xfs_vm_writepages,
+ .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 = iomap_migrate_page,
+ .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,
+ .set_page_dirty = noop_set_page_dirty,
+ .invalidatepage = noop_invalidatepage,
+ .swap_activate = xfs_iomap_swapfile_activate,
+};