On Wed 09-05-18 10:33:19, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Add a new iomap_swapfile_activate function so that filesystems can
> activate swap files without having to use the obsolete and slow bmap
> function. This enables XFS to support fallocate'd swap files and
> swap files on realtime devices.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
The patch looks good to me now. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/iomap.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_aops.c | 12 ++++
> include/linux/iomap.h | 11 +++
> 3 files changed, 185 insertions(+)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index afd163586aa0..99e7f1aa2779 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -27,6 +27,7 @@
> #include <linux/task_io_accounting_ops.h>
> #include <linux/dax.h>
> #include <linux/sched/signal.h>
> +#include <linux/swap.h>
>
> #include "internal.h"
>
> @@ -1089,3 +1090,164 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> return ret;
> }
> EXPORT_SYMBOL_GPL(iomap_dio_rw);
> +
> +/* Swapfile activation */
> +
> +#ifdef CONFIG_SWAP
> +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;
> +
> + /* Skip holes. */
> + if (iomap->type == IOMAP_HOLE)
> + goto out;
> +
> + /* Only one bdev per swap file. */
> + if (iomap->bdev != isi->sis->bdev)
> + goto err;
> +
> + /* Only real or unwritten extents. */
> + if (iomap->type != IOMAP_MAPPED && iomap->type != IOMAP_UNWRITTEN)
> + goto err;
> +
> + /* No uncommitted metadata or shared blocks or inline data. */
> + if (iomap->flags & (IOMAP_F_DIRTY | IOMAP_F_SHARED |
> + IOMAP_F_DATA_INLINE))
> + goto err;
> +
> + /* No null physical addresses. */
> + if (iomap->addr == IOMAP_NULL_ADDR)
> + goto err;
> +
> + 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));
> + }
> +out:
> + return count;
> +err:
> + pr_err("swapon: file cannot be used for swap\n");
> + return -EINVAL;
> +}
> +
> +/*
> + * 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;
> +
> + ret = filemap_write_and_wait(inode->i_mapping);
> + 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);
> +#endif /* CONFIG_SWAP */
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 0ab824f574ed..80de476cecf8 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -1475,6 +1475,16 @@ xfs_vm_set_page_dirty(
> return newly_dirty;
> }
>
> +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,
> @@ -1488,6 +1498,7 @@ const struct address_space_operations xfs_address_space_operations = {
> .migratepage = buffer_migrate_page,
> .is_partially_uptodate = block_is_partially_uptodate,
> .error_remove_page = generic_error_remove_page,
> + .swap_activate = xfs_iomap_swapfile_activate,
> };
>
> const struct address_space_operations xfs_dax_aops = {
> @@ -1495,4 +1506,5 @@ const struct address_space_operations xfs_dax_aops = {
> .direct_IO = noop_direct_IO,
> .set_page_dirty = noop_set_page_dirty,
> .invalidatepage = noop_invalidatepage,
> + .swap_activate = xfs_iomap_swapfile_activate,
> };
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 19a07de28212..4bd87294219a 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -106,4 +106,15 @@ typedef int (iomap_dio_end_io_t)(struct kiocb *iocb, ssize_t ret,
> ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> const struct iomap_ops *ops, iomap_dio_end_io_t end_io);
>
> +#ifdef CONFIG_SWAP
> +struct file;
> +struct swap_info_struct;
> +
> +int iomap_swapfile_activate(struct swap_info_struct *sis,
> + struct file *swap_file, sector_t *pagespan,
> + const struct iomap_ops *ops);
> +#else
> +# define iomap_swapfile_activate(sis, swapfile, pagespan, ops) (-EIO)
> +#endif /* CONFIG_SWAP */
> +
> #endif /* LINUX_IOMAP_H */
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
