iomap: add a swapfile activation function
Subsystems (4)
PATCH 1/1 iomap: add a swapfile activation function
From: Darrick J. Wong <[email protected]>
Add a new iomap_swapfile_activate function so that filesystems can activate swap files without having to use the obsolete and slow bmap function.
Signed-off-by Darrick J. Wong <[email protected]>
--- fs/iomap.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/xfs/xfs_aops.c | 12 ++++++ include/linux/iomap.h | 7 +++ 3 files changed, 118 insertions(+)
fs/iomap.c +99 -0
@@ -1089,3 +1089,102 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,return ret; }EXPORT_SYMBOL_GPL (iomap_dio_rw); + +/* Swapfile activation */ + +struct iomap_swapfile_info { +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 expected_page_no;/* next logical offset wanted (pages) */ +int nr_extents;/* extent count */ +}; + +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; +unsigned long page_no = iomap->offset >>PAGE_SHIFT ; +unsigned long nr_pages = iomap->length >>PAGE_SHIFT ; +uint64_t first_ppage = iomap->addr >>PAGE_SHIFT ; +uint64_t last_ppage = ((iomap->addr + iomap->length) >>PAGE_SHIFT ) -1 ; + +/* Only one bdev per swap file. */ +if (iomap->bdev != isi->sis->bdev) + goto err; + +/* Must be aligned to a page boundary. */ +if ((iomap->offset & ~PAGE_MASK ) || (iomap->addr & ~PAGE_MASK ) || + (iomap->length & ~PAGE_MASK )) + goto err; + +/* Only real or unwritten extents. */ +if (iomap->type !=IOMAP_MAPPED && iomap->type !=IOMAP_UNWRITTEN ) + goto err; + +/* No sparse files. */ +if (isi->expected_page_no != page_no) + 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; + +/* +* Calculate how much swap space we're adding; the first page contains +* the swap header and doesn't count. +*/ +if (page_no ==0 ) + first_ppage++; +if (isi->lowest_ppage > first_ppage) + isi->lowest_ppage = first_ppage; +if (isi->highest_ppage < last_ppage) + isi->highest_ppage = last_ppage; + +/* Add extent, set up for the next call. */ + isi->nr_extents +=add_swap_extent (isi->sis, page_no, nr_pages, + first_ppage); + isi->expected_page_no = page_no + nr_pages; + +return count; +err: +pr_err ("swapon: swapfile has holes\n" ); +return -EINVAL ; +} + +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 =i_size_read (inode); +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; + } + + *pagespan =1 + isi.highest_ppage - isi.lowest_ppage; + sis->max = isi.expected_page_no; + sis->pages = isi.expected_page_no -1 ; + sis->highest_bit = isi.expected_page_no -1 ; +return isi.nr_extents; +} +EXPORT_SYMBOL_GPL (iomap_swapfile_activate);
fs/xfs/xfs_aops.c +12 -0
@@ -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, };
include/linux/iomap.h +7 -0
@@ -106,4 +106,11 @@ 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); +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); +#endif /* LINUX_IOMAP_H */
Jan Kara
reviewerQuoted 18 lines · Darrick J. Wong
fs/iomap.c +18
-0+ +/* Swapfile activation */ + +struct iomap_swapfile_info { +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 expected_page_no;/* next logical offset wanted (pages) */ +int nr_extents;/* extent count */ +}; + +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; +unsigned long page_no = iomap->offset >>PAGE_SHIFT ; +unsigned long nr_pages = iomap->length >>PAGE_SHIFT ; +uint64_t first_ppage = iomap->addr >>PAGE_SHIFT ;
fs/iomap.c iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, · line 1119
Quoted 10 lines
fs/iomap.c +10
-0+uint64_t last_ppage = ((iomap->addr + iomap->length) >>PAGE_SHIFT ) -1 ; + +/* Only one bdev per swap file. */ +if (iomap->bdev != isi->sis->bdev) + goto err; + +/* Must be aligned to a page boundary. */ +if ((iomap->offset & ~PAGE_MASK ) || (iomap->addr & ~PAGE_MASK ) || + (iomap->length & ~PAGE_MASK )) + goto err;
Reporting error in this case does not look equivalent to generic_swapfile_activate()? That function just skips blocks with insufficient alignment... And I'm actually puzzled why alignment of physical block is needed but that's independent question.
Quoted 17 lines
fs/iomap.c +17
-0+/* Only real or unwritten extents. */ +if (iomap->type !=IOMAP_MAPPED && iomap->type !=IOMAP_UNWRITTEN ) + goto err; + +/* No sparse files. */ +if (isi->expected_page_no != page_no) + 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; + +/* +* Calculate how much swap space we're adding; the first page contains +* the swap header and doesn't count. +*/
fs/iomap.c iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, · line 1147
Quoted 10 lines
fs/iomap.c +10
-0+if (page_no ==0 ) + first_ppage++; +if (isi->lowest_ppage > first_ppage) + isi->lowest_ppage = first_ppage; +if (isi->highest_ppage < last_ppage) + isi->highest_ppage = last_ppage; + +/* Add extent, set up for the next call. */ + isi->nr_extents +=add_swap_extent (isi->sis, page_no, nr_pages, + first_ppage);
And here add_swap_extent() can return error.
Honza
Signature · 2 lines
Jan Kara <[email protected]> SUSE Labs, CR
Quoted 25 lines · Jan Kara
Quoted 24 lines · Darrick J. Wong
fs/iomap.c +24
-0+ +/* Swapfile activation */ + +struct iomap_swapfile_info { +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 expected_page_no;/* next logical offset wanted (pages) */ +int nr_extents;/* extent count */ +}; + +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; +unsigned long page_no = iomap->offset >>PAGE_SHIFT ; +unsigned long nr_pages = iomap->length >>PAGE_SHIFT ; +uint64_t first_ppage = iomap->addr >>PAGE_SHIFT ; +uint64_t last_ppage = ((iomap->addr + iomap->length) >>PAGE_SHIFT ) -1 ; + +/* Only one bdev per swap file. */ +if (iomap->bdev != isi->sis->bdev) + goto err; +
Quoted 8 lines
fs/iomap.c iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, · line 1119
Quoted 4 lines
fs/iomap.c +4
-0+/* Must be aligned to a page boundary. */ +if ((iomap->offset & ~PAGE_MASK ) || (iomap->addr & ~PAGE_MASK ) || + (iomap->length & ~PAGE_MASK )) + goto err;Reporting error in this case does not look equivalent to
generic_swapfile_activate()? That function just skips blocks with insufficient alignment...
Yes, I've fixed this to emulate more closely the behavior of the old bmap implementation, so now we collect physically contiguous iomaps and trim the accumulated iomap to satisfy the page alignment requirements.
Quoted 2 lines
And I'm actually puzzled why alignment of physical block is needed but that's independent question.
I'm not sure why either. :)
Quoted 21 lines
Quoted 21 lines
fs/iomap.c +21
-0+/* Only real or unwritten extents. */ +if (iomap->type !=IOMAP_MAPPED && iomap->type !=IOMAP_UNWRITTEN ) + goto err; + +/* No sparse files. */ +if (isi->expected_page_no != page_no) + 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; + +/* +* Calculate how much swap space we're adding; the first page contains +* the swap header and doesn't count. +*/ +if (page_no ==0 ) + first_ppage++; +if (isi->lowest_ppage > first_ppage) + isi->lowest_ppage = first_ppage;
Quoted 8 lines
fs/iomap.c iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, · line 1147
Quoted 6 lines
fs/iomap.c +6
-0+if (isi->highest_ppage < last_ppage) + isi->highest_ppage = last_ppage; + +/* Add extent, set up for the next call. */ + isi->nr_extents +=add_swap_extent (isi->sis, page_no, nr_pages, + first_ppage);And here
add_swap_extent()can return error.
Fixed, thanks.
--D
Quoted 5 lines
Honza
Signature · 2 lines
Jan Kara <[email protected]> SUSE Labs, CR
This looks much better than using bmap, but I still think that having the swap code build its own ineffecient extents maps is a horible idea..
Quoted 172 lines · Darrick J. Wong
From: Darrick J. Wong <[email protected]>
Add a new
iomap_swapfile_activatefunction so that filesystems can activate swap files without having to use the obsolete and slow bmap function.Signed-off-by Darrick J. Wong <[email protected]>--- fs/iomap.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/xfs/xfs_aops.c | 12 ++++++ include/linux/iomap.h | 7 +++ 3 files changed, 118 insertions(+)fs/iomap.c +99
-0@@ -1089,3 +1089,102 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,return ret; }EXPORT_SYMBOL_GPL (iomap_dio_rw); + +/* Swapfile activation */ + +struct iomap_swapfile_info { +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 expected_page_no;/* next logical offset wanted (pages) */ +int nr_extents;/* extent count */ +}; + +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; +unsigned long page_no = iomap->offset >>PAGE_SHIFT ; +unsigned long nr_pages = iomap->length >>PAGE_SHIFT ; +uint64_t first_ppage = iomap->addr >>PAGE_SHIFT ; +uint64_t last_ppage = ((iomap->addr + iomap->length) >>PAGE_SHIFT ) -1 ; + +/* Only one bdev per swap file. */ +if (iomap->bdev != isi->sis->bdev) + goto err; + +/* Must be aligned to a page boundary. */ +if ((iomap->offset & ~PAGE_MASK ) || (iomap->addr & ~PAGE_MASK ) || + (iomap->length & ~PAGE_MASK )) + goto err; + +/* Only real or unwritten extents. */ +if (iomap->type !=IOMAP_MAPPED && iomap->type !=IOMAP_UNWRITTEN ) + goto err; + +/* No sparse files. */ +if (isi->expected_page_no != page_no) + 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; + +/* +* Calculate how much swap space we're adding; the first page contains +* the swap header and doesn't count. +*/ +if (page_no ==0 ) + first_ppage++; +if (isi->lowest_ppage > first_ppage) + isi->lowest_ppage = first_ppage; +if (isi->highest_ppage < last_ppage) + isi->highest_ppage = last_ppage; + +/* Add extent, set up for the next call. */ + isi->nr_extents +=add_swap_extent (isi->sis, page_no, nr_pages, + first_ppage); + isi->expected_page_no = page_no + nr_pages; + +return count; +err: +pr_err ("swapon: swapfile has holes\n" ); +return -EINVAL ; +} + +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 =i_size_read (inode); +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; + } + + *pagespan =1 + isi.highest_ppage - isi.lowest_ppage; + sis->max = isi.expected_page_no; + sis->pages = isi.expected_page_no -1 ; + sis->highest_bit = isi.expected_page_no -1 ; +return isi.nr_extents; +} +EXPORT_SYMBOL_GPL (iomap_swapfile_activate);fs/xfs/xfs_aops.c +12
-0@@ -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, };include/linux/iomap.h +7
-1@@ -106,4 +106,11 @@ 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); +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); +#endif /* LINUX_IOMAP_H */ --
Quoted 3 lines
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Quoted 3 lines · Christoph Hellwig
This looks much better than using bmap, but I still think that having the swap code build its own ineffecient extents maps is a horible idea..
The iomaps that are fed to the actor function are limited in length by the underlying filesystem's extent records, so if we allocate a single 16GB physical extent, xfs creates two 2^20 block extent records and calls the actor on both extents. add_swap_extent merges those into a single internal extent record behind the scenes to satisfy its own requirements and reduce memory usage. The current separation of duties means that the mm code doesn't care about what the fs does internally and the fs doesn't know or care about what the mm does with the information afterwards.
Hey memory management developers, what do you all think of this? Nobody I cornered at LSF pointed out any problems.
(I mean, we /could/ just treat the swapfile as an unbreakable rdma/dax style lease, but ugh...)
--D
Quoted 182 lines · Darrick J. Wong
Quoted 172 lines
From: Darrick J. Wong <[email protected]>
Add a new
iomap_swapfile_activatefunction so that filesystems can activate swap files without having to use the obsolete and slow bmap function.Signed-off-by Darrick J. Wong <[email protected]>--- fs/iomap.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/xfs/xfs_aops.c | 12 ++++++ include/linux/iomap.h | 7 +++ 3 files changed, 118 insertions(+)fs/iomap.c +99
-0@@ -1089,3 +1089,102 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,return ret; }EXPORT_SYMBOL_GPL (iomap_dio_rw); + +/* Swapfile activation */ + +struct iomap_swapfile_info { +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 expected_page_no;/* next logical offset wanted (pages) */ +int nr_extents;/* extent count */ +}; + +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; +unsigned long page_no = iomap->offset >>PAGE_SHIFT ; +unsigned long nr_pages = iomap->length >>PAGE_SHIFT ; +uint64_t first_ppage = iomap->addr >>PAGE_SHIFT ; +uint64_t last_ppage = ((iomap->addr + iomap->length) >>PAGE_SHIFT ) -1 ; + +/* Only one bdev per swap file. */ +if (iomap->bdev != isi->sis->bdev) + goto err; + +/* Must be aligned to a page boundary. */ +if ((iomap->offset & ~PAGE_MASK ) || (iomap->addr & ~PAGE_MASK ) || + (iomap->length & ~PAGE_MASK )) + goto err; + +/* Only real or unwritten extents. */ +if (iomap->type !=IOMAP_MAPPED && iomap->type !=IOMAP_UNWRITTEN ) + goto err; + +/* No sparse files. */ +if (isi->expected_page_no != page_no) + 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; + +/* +* Calculate how much swap space we're adding; the first page contains +* the swap header and doesn't count. +*/ +if (page_no ==0 ) + first_ppage++; +if (isi->lowest_ppage > first_ppage) + isi->lowest_ppage = first_ppage; +if (isi->highest_ppage < last_ppage) + isi->highest_ppage = last_ppage; + +/* Add extent, set up for the next call. */ + isi->nr_extents +=add_swap_extent (isi->sis, page_no, nr_pages, + first_ppage); + isi->expected_page_no = page_no + nr_pages; + +return count; +err: +pr_err ("swapon: swapfile has holes\n" ); +return -EINVAL ; +} + +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 =i_size_read (inode); +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; + } + + *pagespan =1 + isi.highest_ppage - isi.lowest_ppage; + sis->max = isi.expected_page_no; + sis->pages = isi.expected_page_no -1 ; + sis->highest_bit = isi.expected_page_no -1 ; +return isi.nr_extents; +} +EXPORT_SYMBOL_GPL (iomap_swapfile_activate);fs/xfs/xfs_aops.c +12
-0@@ -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, };include/linux/iomap.h +7
-1@@ -106,4 +106,11 @@ 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); +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); +#endif /* LINUX_IOMAP_H */ --Quoted 3 lines
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Quoted 2 lines · Darrick J. Wong
(I mean, we /could/ just treat the swapfile as an unbreakable rdma/dax style lease, but ugh...)
That is what I think it should be long term, instead of a strange parallel I/O path.
But in the mean time we have a real problem with supporting swap files, so we should merge the approaches from you and Aleksei and get something in ASAP.
Quoted 10 lines · Christoph Hellwig
Quoted 2 lines · Darrick J. Wong
(I mean, we /could/ just treat the swapfile as an unbreakable rdma/dax style lease, but ugh...)
That is what I think it should be long term, instead of a strange parallel I/O path.
But in the mean time we have a real problem with supporting swap files, so we should merge the approaches from you and Aleksei and get something in ASAP.
I'm planning to do something along these lines for Btrfs, as well (have swap_activate add the swap extents itself), because the previous thing I tried with going through ->read_iter() and ->write_iter() ran into too many locking issues (i.e., GFP_NOFS can suddenly go through FS locks).