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-rw-r--r--fs/iomap/swapfile.c195
1 files changed, 195 insertions, 0 deletions
diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c
new file mode 100644
index 000000000..5fc0ac36d
--- /dev/null
+++ b/fs/iomap/swapfile.c
@@ -0,0 +1,195 @@
+// 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>
+
+/* 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 */
+ struct file *file;
+};
+
+/*
+ * 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;
+ unsigned long max_pages;
+ uint64_t first_ppage;
+ uint64_t first_ppage_reported;
+ uint64_t next_ppage;
+ int error;
+
+ if (unlikely(isi->nr_pages >= isi->sis->max))
+ return 0;
+ max_pages = isi->sis->max - isi->nr_pages;
+
+ /*
+ * 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;
+ nr_pages = min(nr_pages, max_pages);
+
+ /*
+ * 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;
+}
+
+static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str)
+{
+ char *buf, *p = ERR_PTR(-ENOMEM);
+
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (buf)
+ p = file_path(isi->file, buf, PATH_MAX);
+ pr_err("swapon: file %s %s\n", IS_ERR(p) ? "<unknown>" : p, str);
+ kfree(buf);
+ return -EINVAL;
+}
+
+/*
+ * 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_iter(const struct iomap_iter *iter,
+ struct iomap *iomap, struct iomap_swapfile_info *isi)
+{
+ switch (iomap->type) {
+ case IOMAP_MAPPED:
+ case IOMAP_UNWRITTEN:
+ /* Only real or unwritten extents. */
+ break;
+ case IOMAP_INLINE:
+ /* No inline data. */
+ return iomap_swapfile_fail(isi, "is inline");
+ default:
+ return iomap_swapfile_fail(isi, "has unallocated extents");
+ }
+
+ /* No uncommitted metadata or shared blocks. */
+ if (iomap->flags & IOMAP_F_DIRTY)
+ return iomap_swapfile_fail(isi, "is not committed");
+ if (iomap->flags & IOMAP_F_SHARED)
+ return iomap_swapfile_fail(isi, "has shared extents");
+
+ /* Only one bdev per swap file. */
+ if (iomap->bdev != isi->sis->bdev)
+ return iomap_swapfile_fail(isi, "outside the main device");
+
+ 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. */
+ int error = iomap_swapfile_add_extent(isi);
+ if (error)
+ return error;
+ memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
+ }
+ return iomap_length(iter);
+}
+
+/*
+ * 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 inode *inode = swap_file->f_mapping->host;
+ struct iomap_iter iter = {
+ .inode = inode,
+ .pos = 0,
+ .len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE),
+ .flags = IOMAP_REPORT,
+ };
+ struct iomap_swapfile_info isi = {
+ .sis = sis,
+ .lowest_ppage = (sector_t)-1ULL,
+ .file = swap_file,
+ };
+ int 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 ((ret = iomap_iter(&iter, ops)) > 0)
+ iter.processed = iomap_swapfile_iter(&iter, &iter.iomap, &isi);
+ if (ret < 0)
+ return ret;
+
+ if (isi.iomap.length) {
+ ret = iomap_swapfile_add_extent(&isi);
+ if (ret)
+ return ret;
+ }
+
+ /*
+ * If this swapfile doesn't contain even a single page-aligned
+ * contiguous range of blocks, reject this useless swapfile to
+ * prevent confusion later on.
+ */
+ if (isi.nr_pages == 0) {
+ pr_warn("swapon: Cannot find a single usable page in file.\n");
+ return -EINVAL;
+ }
+
+ *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);