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authorDarrick J. Wong <darrick.wong@oracle.com>2019-07-15 08:50:57 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-07-17 07:14:10 -0700
commita45c0eccc564649541305c71539350c7a890226e (patch)
tree058be82a29cf3217273f622cbc33dbe51269621f /fs/iomap
parent1c230208f53de479352cdb7fa2f851005df7cdc9 (diff)
iomap: move the swapfile code into a separate file
Move the swapfile activation code into a separate file so that we can group related functions in a single file instead of having a single enormous source file. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/iomap')
-rw-r--r--fs/iomap/Makefile3
-rw-r--r--fs/iomap/swapfile.c180
2 files changed, 183 insertions, 0 deletions
diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
index de5a1f914b2c..f88eca22ae80 100644
--- a/fs/iomap/Makefile
+++ b/fs/iomap/Makefile
@@ -3,3 +3,6 @@
# Copyright (c) 2019 Oracle.
# All Rights Reserved.
#
+obj-$(CONFIG_FS_IOMAP) += iomap.o
+
+iomap-$(CONFIG_SWAP) += swapfile.o
diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c
new file mode 100644
index 000000000000..b79c33631263
--- /dev/null
+++ b/fs/iomap/swapfile.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/iomap.h>
+#include <linux/swap.h>
+
+#include "../internal.h"
+
+/* Swapfile activation */
+
+struct iomap_swapfile_info {
+ struct iomap iomap; /* accumulated iomap */
+ struct swap_info_struct *sis;
+ uint64_t lowest_ppage; /* lowest physical addr seen (pages) */
+ uint64_t highest_ppage; /* highest physical addr seen (pages) */
+ unsigned long nr_pages; /* number of pages collected */
+ int nr_extents; /* extent count */
+};
+
+/*
+ * Collect physical extents for this swap file. Physical extents reported to
+ * the swap code must be trimmed to align to a page boundary. The logical
+ * offset within the file is irrelevant since the swapfile code maps logical
+ * page numbers of the swap device to the physical page-aligned extents.
+ */
+static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
+{
+ struct iomap *iomap = &isi->iomap;
+ unsigned long nr_pages;
+ uint64_t first_ppage;
+ uint64_t first_ppage_reported;
+ uint64_t next_ppage;
+ int error;
+
+ /*
+ * Round the start up and the end down so that the physical
+ * extent aligns to a page boundary.
+ */
+ first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
+ next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
+ PAGE_SHIFT;
+
+ /* Skip too-short physical extents. */
+ if (first_ppage >= next_ppage)
+ return 0;
+ nr_pages = next_ppage - first_ppage;
+
+ /*
+ * Calculate how much swap space we're adding; the first page contains
+ * the swap header and doesn't count. The mm still wants that first
+ * page fed to add_swap_extent, however.
+ */
+ first_ppage_reported = first_ppage;
+ if (iomap->offset == 0)
+ first_ppage_reported++;
+ if (isi->lowest_ppage > first_ppage_reported)
+ isi->lowest_ppage = first_ppage_reported;
+ if (isi->highest_ppage < (next_ppage - 1))
+ isi->highest_ppage = next_ppage - 1;
+
+ /* Add extent, set up for the next call. */
+ error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
+ if (error < 0)
+ return error;
+ isi->nr_extents += error;
+ isi->nr_pages += nr_pages;
+ return 0;
+}
+
+/*
+ * Accumulate iomaps for this swap file. We have to accumulate iomaps because
+ * swap only cares about contiguous page-aligned physical extents and makes no
+ * distinction between written and unwritten extents.
+ */
+static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
+ loff_t count, void *data, struct iomap *iomap)
+{
+ struct iomap_swapfile_info *isi = data;
+ int error;
+
+ switch (iomap->type) {
+ case IOMAP_MAPPED:
+ case IOMAP_UNWRITTEN:
+ /* Only real or unwritten extents. */
+ break;
+ case IOMAP_INLINE:
+ /* No inline data. */
+ pr_err("swapon: file is inline\n");
+ return -EINVAL;
+ default:
+ pr_err("swapon: file has unallocated extents\n");
+ return -EINVAL;
+ }
+
+ /* No uncommitted metadata or shared blocks. */
+ if (iomap->flags & IOMAP_F_DIRTY) {
+ pr_err("swapon: file is not committed\n");
+ return -EINVAL;
+ }
+ if (iomap->flags & IOMAP_F_SHARED) {
+ pr_err("swapon: file has shared extents\n");
+ return -EINVAL;
+ }
+
+ /* Only one bdev per swap file. */
+ if (iomap->bdev != isi->sis->bdev) {
+ pr_err("swapon: file is on multiple devices\n");
+ return -EINVAL;
+ }
+
+ if (isi->iomap.length == 0) {
+ /* No accumulated extent, so just store it. */
+ memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
+ } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
+ /* Append this to the accumulated extent. */
+ isi->iomap.length += iomap->length;
+ } else {
+ /* Otherwise, add the retained iomap and store this one. */
+ error = iomap_swapfile_add_extent(isi);
+ if (error)
+ return error;
+ memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
+ }
+ return count;
+}
+
+/*
+ * Iterate a swap file's iomaps to construct physical extents that can be
+ * passed to the swapfile subsystem.
+ */
+int iomap_swapfile_activate(struct swap_info_struct *sis,
+ struct file *swap_file, sector_t *pagespan,
+ const struct iomap_ops *ops)
+{
+ struct iomap_swapfile_info isi = {
+ .sis = sis,
+ .lowest_ppage = (sector_t)-1ULL,
+ };
+ struct address_space *mapping = swap_file->f_mapping;
+ struct inode *inode = mapping->host;
+ loff_t pos = 0;
+ loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
+ loff_t ret;
+
+ /*
+ * Persist all file mapping metadata so that we won't have any
+ * IOMAP_F_DIRTY iomaps.
+ */
+ ret = vfs_fsync(swap_file, 1);
+ if (ret)
+ return ret;
+
+ while (len > 0) {
+ ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
+ ops, &isi, iomap_swapfile_activate_actor);
+ if (ret <= 0)
+ return ret;
+
+ pos += ret;
+ len -= ret;
+ }
+
+ if (isi.iomap.length) {
+ ret = iomap_swapfile_add_extent(&isi);
+ if (ret)
+ return ret;
+ }
+
+ *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
+ sis->max = isi.nr_pages;
+ sis->pages = isi.nr_pages - 1;
+ sis->highest_bit = isi.nr_pages - 1;
+ return isi.nr_extents;
+}
+EXPORT_SYMBOL_GPL(iomap_swapfile_activate);

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