From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 10 May 2018 15:36:46 +0200 From: Jan Kara To: "Darrick J. Wong" Cc: hch@infradead.org, xfs , Jan Kara , linux-fsdevel , linux-mm@kvack.org, cyberax@amazon.com, osandov@osandov.com, Eryu Guan Subject: Re: [PATCH v4] iomap: add a swapfile activation function Message-ID: <20180510133646.kq5aacwrvpsu3gwj@quack2.suse.cz> References: <20180509173319.GE9510@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180509173319.GE9510@magnolia> Sender: owner-linux-mm@kvack.org List-ID: On Wed 09-05-18 10:33:19, Darrick J. Wong wrote: > From: Darrick J. Wong > > 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 The patch looks good to me now. You can add: Reviewed-by: Jan Kara 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 > #include > #include > +#include > > #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 SUSE Labs, CR