[v3,1/2] iomap: add a swapfile activation function

Message ID	20180503174659.GD4127@magnolia (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> Date: Thu, 3 May 2018 10:46:59 -0700 From: "Darrick J. Wong" <darrick.wong@oracle.com> To: xfs <linux-xfs@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, linux-mm@kvack.org Cc: hch@infradead.org, cyberax@amazon.com, jack@suse.cz, osandov@osandov.com, Eryu Guan <guaneryu@gmail.com> Subject: [PATCH v3 1/2] iomap: add a swapfile activation function Message-ID: <20180503174659.GD4127@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk

diff --git a/fs/iomap.c b/fs/iomap.c index afd163586aa0..ac7115492366 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 last_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; + last_ppage = (ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >> + PAGE_SHIFT) - 1; + + /* Skip too-short physical extents. */ + if (first_ppage > last_ppage) + return 0; + nr_pages = last_ppage - first_ppage + 1; + + /* + * 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 < last_ppage) + isi->highest_ppage = last_ppage; + + /* 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 */

[v3,1/2] iomap: add a swapfile activation function

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