On Thu, Jun 24, 2021 at 08:49:17AM +0000, [email protected] wrote: > Hi Darrick, > > Do you have any comment on this?
Sorry, was on vacation. > Thanks, > Ruan. > > > -----Original Message----- > > From: Shiyang Ruan <[email protected]> > > Subject: [PATCH v6.1 6/7] fs/xfs: Handle CoW for fsdax write() path > > > > Hi Darrick, > > > > Since other patches looks good, I post this RFC patch singly to hot-fix the > > problem in xfs_dax_write_iomap_ops->iomap_end() of v6 that the error code > > was ingored. I will split this in two patches(changes in iomap and xfs > > respectively) in next formal version if it looks ok. > > > > ==== > > > > Introduce a new interface called "iomap_post_actor()" in iomap_ops. And > > call > > it between ->actor() and ->iomap_end(). It is mean to handle the error code > > returned from ->actor(). In this patchset, it is used to remap or cancel > > the > > CoW extents according to the error code. > > > > Signed-off-by: Shiyang Ruan <[email protected]> > > --- > > fs/dax.c | 27 ++++++++++++++++++--------- > > fs/iomap/apply.c | 4 ++++ > > fs/xfs/xfs_bmap_util.c | 3 +-- > > fs/xfs/xfs_file.c | 5 +++-- > > fs/xfs/xfs_iomap.c | 33 ++++++++++++++++++++++++++++++++- > > fs/xfs/xfs_iomap.h | 24 ++++++++++++++++++++++++ > > fs/xfs/xfs_iops.c | 7 +++---- > > fs/xfs/xfs_reflink.c | 3 +-- > > include/linux/iomap.h | 8 ++++++++ > > 9 files changed, 94 insertions(+), 20 deletions(-) > > > > diff --git a/fs/dax.c b/fs/dax.c > > index 93f16210847b..0740c2610b6f 100644 > > --- a/fs/dax.c > > +++ b/fs/dax.c > > @@ -1537,7 +1537,7 @@ static vm_fault_t dax_iomap_pte_fault(struct > > vm_fault *vmf, pfn_t *pfnp, > > struct iomap iomap = { .type = IOMAP_HOLE }; > > struct iomap srcmap = { .type = IOMAP_HOLE }; > > unsigned flags = IOMAP_FAULT; > > - int error; > > + int error, copied = PAGE_SIZE; > > bool write = vmf->flags & FAULT_FLAG_WRITE; > > vm_fault_t ret = 0, major = 0; > > void *entry; > > @@ -1598,7 +1598,7 @@ static vm_fault_t dax_iomap_pte_fault(struct > > vm_fault *vmf, pfn_t *pfnp, > > ret = dax_fault_actor(vmf, pfnp, &xas, &entry, false, flags, > > &iomap, &srcmap); > > if (ret == VM_FAULT_SIGBUS) > > - goto finish_iomap; > > + goto finish_iomap_actor; > > > > /* read/write MAPPED, CoW UNWRITTEN */ > > if (iomap.flags & IOMAP_F_NEW) { > > @@ -1607,10 +1607,16 @@ static vm_fault_t dax_iomap_pte_fault(struct > > vm_fault *vmf, pfn_t *pfnp, > > major = VM_FAULT_MAJOR; > > } > > > > + finish_iomap_actor: > > + if (ops->iomap_post_actor) { > > + if (ret & VM_FAULT_ERROR) > > + copied = 0; > > + ops->iomap_post_actor(inode, pos, PMD_SIZE, copied, flags, > > + &iomap, &srcmap); > > + } > > + > > finish_iomap: > > if (ops->iomap_end) { > > - int copied = PAGE_SIZE; > > - > > if (ret & VM_FAULT_ERROR) > > copied = 0; > > /* > > @@ -1677,7 +1683,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct > > vm_fault *vmf, pfn_t *pfnp, > > pgoff_t max_pgoff; > > void *entry; > > loff_t pos; > > - int error; > > + int error, copied = PMD_SIZE; > > > > /* > > * Check whether offset isn't beyond end of file now. Caller is @@ > > -1736,12 > > +1742,15 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, > > pfn_t *pfnp, > > ret = dax_fault_actor(vmf, pfnp, &xas, &entry, true, flags, > > &iomap, &srcmap); > > > > + if (ret == VM_FAULT_FALLBACK) > > + copied = 0; > > + if (ops->iomap_post_actor) { > > + ops->iomap_post_actor(inode, pos, PMD_SIZE, copied, flags, > > + &iomap, &srcmap); > > + } > > + > > finish_iomap: > > if (ops->iomap_end) { > > - int copied = PMD_SIZE; > > - > > - if (ret == VM_FAULT_FALLBACK) > > - copied = 0; > > /* > > * The fault is done by now and there's no way back (other > > * thread may be already happily using PMD we have installed). > > diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c index > > 0493da5286ad..26a54ded184f 100644 > > --- a/fs/iomap/apply.c > > +++ b/fs/iomap/apply.c > > @@ -84,6 +84,10 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t > > length, > > unsigned flags, > > written = actor(inode, pos, length, data, &iomap, > > srcmap.type != IOMAP_HOLE ? &srcmap : &iomap); > > > > + if (ops->iomap_post_actor) { > > + written = ops->iomap_post_actor(inode, pos, length, written, > > + flags, &iomap, &srcmap); How many operations actually need an iomap_post_actor? It's just the dax ones, right? Which is ... iomap_truncate_page, iomap_zero_range, dax_iomap_fault, and dax_iomap_rw, right? We don't need a post_actor for other iomap functionality (like FIEMAP, SEEK_DATA/SEEK_HOLE, etc.) so adding a new function pointer for all operations feels a bit overbroad. I had imagined that you'd create a struct dax_iomap_ops to wrap all the extra functionality that you need for dax operations: struct dax_iomap_ops { struct iomap_ops iomap_ops; int (*end_io)(inode, pos, length...); }; And alter the four functions that you need to take the special dax_iomap_ops. I guess the downside is that this makes iomap_truncate_page and iomap_zero_range more complicated, but maybe it's just time to split those into DAX-specific versions. Then we'd be rid of the cross-links betwee fs/iomap/buffered-io.c and fs/dax.c. > > + } > > out: > > /* > > * Now the data has been copied, commit the range we've copied. This > > diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index > > a5e9d7d34023..2a36dc93ff27 100644 > > --- a/fs/xfs/xfs_bmap_util.c > > +++ b/fs/xfs/xfs_bmap_util.c > > @@ -965,8 +965,7 @@ xfs_free_file_space( > > return 0; > > if (offset + len > XFS_ISIZE(ip)) > > len = XFS_ISIZE(ip) - offset; > > - error = iomap_zero_range(VFS_I(ip), offset, len, NULL, > > - &xfs_buffered_write_iomap_ops); > > + error = xfs_iomap_zero_range(ip, offset, len, NULL); > > if (error) > > return error; > > > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index > > 396ef36dcd0a..89406ec6741b > > 100644 > > --- a/fs/xfs/xfs_file.c > > +++ b/fs/xfs/xfs_file.c > > @@ -684,11 +684,12 @@ xfs_file_dax_write( > > pos = iocb->ki_pos; > > > > trace_xfs_file_dax_write(iocb, from); > > - ret = dax_iomap_rw(iocb, from, &xfs_direct_write_iomap_ops); > > + ret = dax_iomap_rw(iocb, from, &xfs_dax_write_iomap_ops); > > if (ret > 0 && iocb->ki_pos > i_size_read(inode)) { > > i_size_write(inode, iocb->ki_pos); > > error = xfs_setfilesize(ip, pos, ret); > > } > > + > > out: > > if (iolock) > > xfs_iunlock(ip, iolock); > > @@ -1309,7 +1310,7 @@ __xfs_filemap_fault( > > > > ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL, > > (write_fault && !vmf->cow_page) ? > > - &xfs_direct_write_iomap_ops : > > + &xfs_dax_write_iomap_ops : > > &xfs_read_iomap_ops); > > if (ret & VM_FAULT_NEEDDSYNC) > > ret = dax_finish_sync_fault(vmf, pe_size, pfn); diff > > --git > > a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index d154f42e2dc6..2f322e2f8544 > > 100644 > > --- a/fs/xfs/xfs_iomap.c > > +++ b/fs/xfs/xfs_iomap.c > > @@ -761,7 +761,8 @@ xfs_direct_write_iomap_begin( > > > > /* may drop and re-acquire the ilock */ > > error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared, > > - &lockmode, flags & IOMAP_DIRECT); > > + &lockmode, > > + (flags & IOMAP_DIRECT) || IS_DAX(inode)); > > if (error) > > goto out_unlock; > > if (shared) > > @@ -854,6 +855,36 @@ const struct iomap_ops xfs_direct_write_iomap_ops = > > { > > .iomap_begin = xfs_direct_write_iomap_begin, > > }; > > > > +static int > > +xfs_dax_write_iomap_post_actor( > > + struct inode *inode, > > + loff_t pos, > > + loff_t length, > > + ssize_t written, > > + unsigned int flags, > > + struct iomap *iomap, > > + struct iomap *srcmap) > > +{ > > + int error = 0; > > + struct xfs_inode *ip = XFS_I(inode); > > + bool cow = xfs_is_cow_inode(ip); > > + > > + if (written <= 0) { > > + if (cow) > > + xfs_reflink_cancel_cow_range(ip, pos, length, true); > > + return written; > > + } > > + > > + if (cow) > > + error = xfs_reflink_end_cow(ip, pos, written); > > + return error ?: written; > > +} This is pretty much the same as what xfs_dio_write_end_io does, right? I had imagined that you'd change the function signatures to drop the iocb so that you could reuse this code instead of creating a whole new callback. Ah well. Can I send you some prep patches to clean up some of the weird iomap code as a preparation series for this? --D > > + > > +const struct iomap_ops xfs_dax_write_iomap_ops = { > > + .iomap_begin = xfs_direct_write_iomap_begin, > > + .iomap_post_actor = xfs_dax_write_iomap_post_actor, > > +}; > > + > > static int > > xfs_buffered_write_iomap_begin( > > struct inode *inode, > > diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h index > > 7d3703556d0e..fbacf638ab21 100644 > > --- a/fs/xfs/xfs_iomap.h > > +++ b/fs/xfs/xfs_iomap.h > > @@ -42,8 +42,32 @@ xfs_aligned_fsb_count( > > > > extern const struct iomap_ops xfs_buffered_write_iomap_ops; extern const > > struct iomap_ops xfs_direct_write_iomap_ops; > > +extern const struct iomap_ops xfs_dax_write_iomap_ops; > > extern const struct iomap_ops xfs_read_iomap_ops; extern const struct > > iomap_ops xfs_seek_iomap_ops; extern const struct iomap_ops > > xfs_xattr_iomap_ops; > > > > +static inline int > > +xfs_iomap_zero_range( > > + struct xfs_inode *ip, > > + loff_t offset, > > + loff_t len, > > + bool *did_zero) > > +{ > > + return iomap_zero_range(VFS_I(ip), offset, len, did_zero, > > + IS_DAX(VFS_I(ip)) ? &xfs_dax_write_iomap_ops > > + : &xfs_buffered_write_iomap_ops); } > > + > > +static inline int > > +xfs_iomap_truncate_page( > > + struct xfs_inode *ip, > > + loff_t pos, > > + bool *did_zero) > > +{ > > + return iomap_truncate_page(VFS_I(ip), pos, did_zero, > > + IS_DAX(VFS_I(ip)) ? &xfs_dax_write_iomap_ops > > + : &xfs_buffered_write_iomap_ops); } > > + > > #endif /* __XFS_IOMAP_H__*/ > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index > > dfe24b7f26e5..6d936c3e1a6e 100644 > > --- a/fs/xfs/xfs_iops.c > > +++ b/fs/xfs/xfs_iops.c > > @@ -911,8 +911,8 @@ xfs_setattr_size( > > */ > > if (newsize > oldsize) { > > trace_xfs_zero_eof(ip, oldsize, newsize - oldsize); > > - error = iomap_zero_range(inode, oldsize, newsize - oldsize, > > - &did_zeroing, &xfs_buffered_write_iomap_ops); > > + error = xfs_iomap_zero_range(ip, oldsize, newsize - oldsize, > > + &did_zeroing); > > } else { > > /* > > * iomap won't detect a dirty page over an unwritten block (or > > a @@ > > -924,8 +924,7 @@ xfs_setattr_size( > > newsize); > > if (error) > > return error; > > - error = iomap_truncate_page(inode, newsize, &did_zeroing, > > - &xfs_buffered_write_iomap_ops); > > + error = xfs_iomap_truncate_page(ip, newsize, &did_zeroing); > > } > > > > if (error) > > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index > > d25434f93235..9a780948dbd0 100644 > > --- a/fs/xfs/xfs_reflink.c > > +++ b/fs/xfs/xfs_reflink.c > > @@ -1266,8 +1266,7 @@ xfs_reflink_zero_posteof( > > return 0; > > > > trace_xfs_zero_eof(ip, isize, pos - isize); > > - return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL, > > - &xfs_buffered_write_iomap_ops); > > + return xfs_iomap_zero_range(ip, isize, pos - isize, NULL); > > } > > > > /* > > diff --git a/include/linux/iomap.h b/include/linux/iomap.h index > > 95562f863ad0..58f2e1c78018 100644 > > --- a/include/linux/iomap.h > > +++ b/include/linux/iomap.h > > @@ -135,6 +135,14 @@ struct iomap_ops { > > unsigned flags, struct iomap *iomap, > > struct iomap *srcmap); > > > > + /* > > + * Handle the error code from actor(). Do the finishing jobs for extra > > + * operations, such as CoW, according to whether written is negative. > > + */ > > + int (*iomap_post_actor)(struct inode *inode, loff_t pos, loff_t length, > > + ssize_t written, unsigned flags, struct iomap *iomap, > > + struct iomap *srcmap); > > + > > /* > > * Commit and/or unreserve space previous allocated using iomap_begin. > > * Written indicates the length of the successful write operation which > > -- > > 2.31.1 >
