On Fri, Jun 21, 2019 at 02:28:23PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <[email protected]> > > Introduces a new type IOMAP_COW, which means the data at offset > must be read from a srcmap and copied before performing the > write on the offset. > > The srcmap is used to identify where the read is to be performed > from. This is passed to iomap->begin(), which is supposed to > put in the details for reading, typically set with type IOMAP_READ.
What is IOMAP_READ ? > > Signed-off-by: Goldwyn Rodrigues <[email protected]> > --- > fs/dax.c | 8 +++++--- > fs/ext2/inode.c | 2 +- > fs/ext4/inode.c | 2 +- > fs/gfs2/bmap.c | 3 ++- > fs/internal.h | 2 +- > fs/iomap.c | 31 ++++++++++++++++--------------- > fs/xfs/xfs_iomap.c | 9 ++++++--- > include/linux/iomap.h | 4 +++- > 8 files changed, 35 insertions(+), 26 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 2e48c7ebb973..80b9e2599223 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1078,7 +1078,7 @@ EXPORT_SYMBOL_GPL(__dax_zero_page_range); > > static loff_t > dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > - struct iomap *iomap) > + struct iomap *iomap, struct iomap *srcmap) > { > struct block_device *bdev = iomap->bdev; > struct dax_device *dax_dev = iomap->dax_dev; > @@ -1236,6 +1236,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault > *vmf, pfn_t *pfnp, > unsigned long vaddr = vmf->address; > loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; > struct iomap iomap = { 0 }; > + struct iomap srcmap = { 0 }; > unsigned flags = IOMAP_FAULT; > int error, major = 0; > bool write = vmf->flags & FAULT_FLAG_WRITE; > @@ -1280,7 +1281,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault > *vmf, pfn_t *pfnp, > * the file system block size to be equal the page size, which means > * that we never have to deal with more than a single extent here. > */ > - error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap); > + error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap, &srcmap); > if (iomap_errp) > *iomap_errp = error; > if (error) { > @@ -1460,6 +1461,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault > *vmf, pfn_t *pfnp, > struct inode *inode = mapping->host; > vm_fault_t result = VM_FAULT_FALLBACK; > struct iomap iomap = { 0 }; > + struct iomap srcmap = { 0 }; > pgoff_t max_pgoff; > void *entry; > loff_t pos; > @@ -1534,7 +1536,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault > *vmf, pfn_t *pfnp, > * to look up our filesystem block. > */ > pos = (loff_t)xas.xa_index << PAGE_SHIFT; > - error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap); > + error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap, > &srcmap); Line too long? Also, I guess the DAX and directio write paths will just WARN_ON_ONCE if someone feeds them an IOMAP_COW type iomap? Ah, right, I guess the only filesystems that use iomap directio and iomap dax don't support COW. :) --D > if (error) > goto unlock_entry; > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c > index e474127dd255..f081f11980ad 100644 > --- a/fs/ext2/inode.c > +++ b/fs/ext2/inode.c > @@ -801,7 +801,7 @@ int ext2_get_block(struct inode *inode, sector_t iblock, > > #ifdef CONFIG_FS_DAX > static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t > length, > - unsigned flags, struct iomap *iomap) > + unsigned flags, struct iomap *iomap, struct iomap *srcmap) > { > unsigned int blkbits = inode->i_blkbits; > unsigned long first_block = offset >> blkbits; > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index c7f77c643008..a8017e0c302b 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3437,7 +3437,7 @@ static bool ext4_inode_datasync_dirty(struct inode > *inode) > } > > static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t > length, > - unsigned flags, struct iomap *iomap) > + unsigned flags, struct iomap *iomap, struct iomap > *srcmap) > { > struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); > unsigned int blkbits = inode->i_blkbits; > diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c > index 93ea1d529aa3..affa0c4305b7 100644 > --- a/fs/gfs2/bmap.c > +++ b/fs/gfs2/bmap.c > @@ -1124,7 +1124,8 @@ static int gfs2_iomap_begin_write(struct inode *inode, > loff_t pos, > } > > static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, > - unsigned flags, struct iomap *iomap) > + unsigned flags, struct iomap *iomap, > + struct iomap *srcmap) > { > struct gfs2_inode *ip = GFS2_I(inode); > struct metapath mp = { .mp_aheight = 1, }; > diff --git a/fs/internal.h b/fs/internal.h > index a48ef81be37d..79e495d86165 100644 > --- a/fs/internal.h > +++ b/fs/internal.h > @@ -188,7 +188,7 @@ extern int do_vfs_ioctl(struct file *file, unsigned int > fd, unsigned int cmd, > * iomap support: > */ > typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len, > - void *data, struct iomap *iomap); > + void *data, struct iomap *iomap, struct iomap *srcmap); > > loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length, > unsigned flags, const struct iomap_ops *ops, void *data, > diff --git a/fs/iomap.c b/fs/iomap.c > index 23ef63fd1669..6648957af268 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -41,6 +41,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, > unsigned flags, > const struct iomap_ops *ops, void *data, iomap_actor_t actor) > { > struct iomap iomap = { 0 }; > + struct iomap srcmap = { 0 }; > loff_t written = 0, ret; > > /* > @@ -55,7 +56,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, > unsigned flags, > * expose transient stale data. If the reserve fails, we can safely > * back out at this point as there is nothing to undo. > */ > - ret = ops->iomap_begin(inode, pos, length, flags, &iomap); > + ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap); > if (ret) > return ret; > if (WARN_ON(iomap.offset > pos)) > @@ -75,7 +76,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, > unsigned flags, > * we can do the copy-in page by page without having to worry about > * failures exposing transient data. > */ > - written = actor(inode, pos, length, data, &iomap); > + written = actor(inode, pos, length, data, &iomap, &srcmap); > > /* > * Now the data has been copied, commit the range we've copied. This > @@ -282,7 +283,7 @@ iomap_read_inline_data(struct inode *inode, struct page > *page, > > static loff_t > iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void > *data, > - struct iomap *iomap) > + struct iomap *iomap, struct iomap *srcmap) > { > struct iomap_readpage_ctx *ctx = data; > struct page *page = ctx->cur_page; > @@ -424,7 +425,7 @@ iomap_next_page(struct inode *inode, struct list_head > *pages, loff_t pos, > > static loff_t > iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > struct iomap_readpage_ctx *ctx = data; > loff_t done, ret; > @@ -444,7 +445,7 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, > loff_t length, > ctx->cur_page_in_bio = false; > } > ret = iomap_readpage_actor(inode, pos + done, length - done, > - ctx, iomap); > + ctx, iomap, srcmap); > } > > return done; > @@ -796,7 +797,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned > len, > > static loff_t > iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > - struct iomap *iomap) > + struct iomap *iomap, struct iomap *srcmap) > { > struct iov_iter *i = data; > long status = 0; > @@ -913,7 +914,7 @@ __iomap_read_page(struct inode *inode, loff_t offset) > > static loff_t > iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > - struct iomap *iomap) > + struct iomap *iomap, struct iomap *srcmap) > { > long status = 0; > ssize_t written = 0; > @@ -1002,7 +1003,7 @@ static int iomap_dax_zero(loff_t pos, unsigned offset, > unsigned bytes, > > static loff_t > iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > bool *did_zero = data; > loff_t written = 0; > @@ -1071,7 +1072,7 @@ EXPORT_SYMBOL_GPL(iomap_truncate_page); > > static loff_t > iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > struct page *page = data; > int ret; > @@ -1169,7 +1170,7 @@ static int iomap_to_fiemap(struct fiemap_extent_info > *fi, > > static loff_t > iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void > *data, > - struct iomap *iomap) > + struct iomap *iomap, struct iomap *srcmap) > { > struct fiemap_ctx *ctx = data; > loff_t ret = length; > @@ -1343,7 +1344,7 @@ page_cache_seek_hole_data(struct inode *inode, loff_t > offset, loff_t length, > > static loff_t > iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > switch (iomap->type) { > case IOMAP_UNWRITTEN: > @@ -1389,7 +1390,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_hole); > > static loff_t > iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > switch (iomap->type) { > case IOMAP_HOLE: > @@ -1790,7 +1791,7 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, > loff_t length, > > static loff_t > iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > struct iomap_dio *dio = data; > > @@ -2057,7 +2058,7 @@ static int iomap_swapfile_add_extent(struct > iomap_swapfile_info *isi) > * 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) > + loff_t count, void *data, struct iomap *iomap, struct iomap > *srcmap) > { > struct iomap_swapfile_info *isi = data; > int error; > @@ -2161,7 +2162,7 @@ EXPORT_SYMBOL_GPL(iomap_swapfile_activate); > > static loff_t > iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length, > - void *data, struct iomap *iomap) > + void *data, struct iomap *iomap, struct iomap *srcmap) > { > sector_t *bno = data, addr; > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index 63d323916bba..6116a75f03da 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -925,7 +925,8 @@ xfs_file_iomap_begin( > loff_t offset, > loff_t length, > unsigned flags, > - struct iomap *iomap) > + struct iomap *iomap, > + struct iomap *srcmap) > { > struct xfs_inode *ip = XFS_I(inode); > struct xfs_mount *mp = ip->i_mount; > @@ -1148,7 +1149,8 @@ xfs_seek_iomap_begin( > loff_t offset, > loff_t length, > unsigned flags, > - struct iomap *iomap) > + struct iomap *iomap, > + struct iomap *srcmap) > { > struct xfs_inode *ip = XFS_I(inode); > struct xfs_mount *mp = ip->i_mount; > @@ -1234,7 +1236,8 @@ xfs_xattr_iomap_begin( > loff_t offset, > loff_t length, > unsigned flags, > - struct iomap *iomap) > + struct iomap *iomap, > + struct iomap *srcmap) > { > struct xfs_inode *ip = XFS_I(inode); > struct xfs_mount *mp = ip->i_mount; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 2103b94cb1bf..f49767c7fd83 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -25,6 +25,7 @@ struct vm_fault; > #define IOMAP_MAPPED 0x03 /* blocks allocated at @addr */ > #define IOMAP_UNWRITTEN 0x04 /* blocks allocated at @addr in > unwritten state */ > #define IOMAP_INLINE 0x05 /* data inline in the inode */ > +#define IOMAP_COW 0x06 /* copy data from srcmap before writing */ > > /* > * Flags for all iomap mappings: > @@ -102,7 +103,8 @@ struct iomap_ops { > * The actual length is returned in iomap->length. > */ > int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length, > - unsigned flags, struct iomap *iomap); > + unsigned flags, struct iomap *iomap, > + struct iomap *srcmap); > > /* > * Commit and/or unreserve space previous allocated using iomap_begin. > -- > 2.16.4 >
