From 63e95b5c4f16e156b98adcf2f7d820ba941c82a3 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Tue, 8 Nov 2016 11:32:20 +1100 Subject: dax: coordinate locking for offsets in PMD range DAX radix tree locking currently locks entries based on the unique combination of the 'mapping' pointer and the pgoff_t 'index' for the entry. This works for PTEs, but as we move to PMDs we will need to have all the offsets within the range covered by the PMD to map to the same bit lock. To accomplish this, for ranges covered by a PMD entry we will instead lock based on the page offset of the beginning of the PMD entry. The 'mapping' pointer is still used in the same way. Signed-off-by: Ross Zwisler Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Dave Chinner --- include/linux/dax.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/dax.h b/include/linux/dax.h index add6c4bc568f..a41a747d6112 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -22,7 +22,7 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index); void dax_wake_mapping_entry_waiter(struct address_space *mapping, - pgoff_t index, bool wake_all); + pgoff_t index, void *entry, bool wake_all); #ifdef CONFIG_FS_DAX struct page *read_dax_sector(struct block_device *bdev, sector_t n); -- cgit v1.2.3 From b9fde0462e34a05b25c3d68d344971865659abae Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Tue, 8 Nov 2016 11:32:35 +1100 Subject: dax: remove dax_pmd_fault() dax_pmd_fault() is the old struct buffer_head + get_block_t based 2 MiB DAX fault handler. This fault handler has been disabled for several kernel releases, and support for PMDs will be reintroduced using the struct iomap interface instead. Signed-off-by: Ross Zwisler Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Dave Chinner --- fs/dax.c | 213 ---------------------------------------------------- include/linux/dax.h | 6 +- 2 files changed, 1 insertion(+), 218 deletions(-) (limited to 'include/linux') diff --git a/fs/dax.c b/fs/dax.c index 72387023545e..3d0b1032c555 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -915,219 +915,6 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } EXPORT_SYMBOL_GPL(dax_fault); -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) -/* - * The 'colour' (ie low bits) within a PMD of a page offset. This comes up - * more often than one might expect in the below function. - */ -#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) - -static void __dax_dbg(struct buffer_head *bh, unsigned long address, - const char *reason, const char *fn) -{ - if (bh) { - char bname[BDEVNAME_SIZE]; - bdevname(bh->b_bdev, bname); - pr_debug("%s: %s addr: %lx dev %s state %lx start %lld " - "length %zd fallback: %s\n", fn, current->comm, - address, bname, bh->b_state, (u64)bh->b_blocknr, - bh->b_size, reason); - } else { - pr_debug("%s: %s addr: %lx fallback: %s\n", fn, - current->comm, address, reason); - } -} - -#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd") - -/** - * dax_pmd_fault - handle a PMD fault on a DAX file - * @vma: The virtual memory area where the fault occurred - * @vmf: The description of the fault - * @get_block: The filesystem method used to translate file offsets to blocks - * - * When a page fault occurs, filesystems may call this helper in their - * pmd_fault handler for DAX files. - */ -int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, - pmd_t *pmd, unsigned int flags, get_block_t get_block) -{ - struct file *file = vma->vm_file; - struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - struct buffer_head bh; - unsigned blkbits = inode->i_blkbits; - unsigned long pmd_addr = address & PMD_MASK; - bool write = flags & FAULT_FLAG_WRITE; - struct block_device *bdev; - pgoff_t size, pgoff; - sector_t block; - int result = 0; - bool alloc = false; - - /* dax pmd mappings require pfn_t_devmap() */ - if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) - return VM_FAULT_FALLBACK; - - /* Fall back to PTEs if we're going to COW */ - if (write && !(vma->vm_flags & VM_SHARED)) { - split_huge_pmd(vma, pmd, address); - dax_pmd_dbg(NULL, address, "cow write"); - return VM_FAULT_FALLBACK; - } - /* If the PMD would extend outside the VMA */ - if (pmd_addr < vma->vm_start) { - dax_pmd_dbg(NULL, address, "vma start unaligned"); - return VM_FAULT_FALLBACK; - } - if ((pmd_addr + PMD_SIZE) > vma->vm_end) { - dax_pmd_dbg(NULL, address, "vma end unaligned"); - return VM_FAULT_FALLBACK; - } - - pgoff = linear_page_index(vma, pmd_addr); - size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (pgoff >= size) - return VM_FAULT_SIGBUS; - /* If the PMD would cover blocks out of the file */ - if ((pgoff | PG_PMD_COLOUR) >= size) { - dax_pmd_dbg(NULL, address, - "offset + huge page size > file size"); - return VM_FAULT_FALLBACK; - } - - memset(&bh, 0, sizeof(bh)); - bh.b_bdev = inode->i_sb->s_bdev; - block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); - - bh.b_size = PMD_SIZE; - - if (get_block(inode, block, &bh, 0) != 0) - return VM_FAULT_SIGBUS; - - if (!buffer_mapped(&bh) && write) { - if (get_block(inode, block, &bh, 1) != 0) - return VM_FAULT_SIGBUS; - alloc = true; - WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh)); - } - - bdev = bh.b_bdev; - - if (bh.b_size < PMD_SIZE) { - dax_pmd_dbg(&bh, address, "allocated block too small"); - return VM_FAULT_FALLBACK; - } - - /* - * If we allocated new storage, make sure no process has any - * zero pages covering this hole - */ - if (alloc) { - loff_t lstart = pgoff << PAGE_SHIFT; - loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */ - - truncate_pagecache_range(inode, lstart, lend); - } - - if (!write && !buffer_mapped(&bh)) { - spinlock_t *ptl; - pmd_t entry; - struct page *zero_page = mm_get_huge_zero_page(vma->vm_mm); - - if (unlikely(!zero_page)) { - dax_pmd_dbg(&bh, address, "no zero page"); - goto fallback; - } - - ptl = pmd_lock(vma->vm_mm, pmd); - if (!pmd_none(*pmd)) { - spin_unlock(ptl); - dax_pmd_dbg(&bh, address, "pmd already present"); - goto fallback; - } - - dev_dbg(part_to_dev(bdev->bd_part), - "%s: %s addr: %lx pfn: sect: %llx\n", - __func__, current->comm, address, - (unsigned long long) to_sector(&bh, inode)); - - entry = mk_pmd(zero_page, vma->vm_page_prot); - entry = pmd_mkhuge(entry); - set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); - result = VM_FAULT_NOPAGE; - spin_unlock(ptl); - } else { - struct blk_dax_ctl dax = { - .sector = to_sector(&bh, inode), - .size = PMD_SIZE, - }; - long length = dax_map_atomic(bdev, &dax); - - if (length < 0) { - dax_pmd_dbg(&bh, address, "dax-error fallback"); - goto fallback; - } - if (length < PMD_SIZE) { - dax_pmd_dbg(&bh, address, "dax-length too small"); - dax_unmap_atomic(bdev, &dax); - goto fallback; - } - if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) { - dax_pmd_dbg(&bh, address, "pfn unaligned"); - dax_unmap_atomic(bdev, &dax); - goto fallback; - } - - if (!pfn_t_devmap(dax.pfn)) { - dax_unmap_atomic(bdev, &dax); - dax_pmd_dbg(&bh, address, "pfn not in memmap"); - goto fallback; - } - dax_unmap_atomic(bdev, &dax); - - /* - * For PTE faults we insert a radix tree entry for reads, and - * leave it clean. Then on the first write we dirty the radix - * tree entry via the dax_pfn_mkwrite() path. This sequence - * allows the dax_pfn_mkwrite() call to be simpler and avoid a - * call into get_block() to translate the pgoff to a sector in - * order to be able to create a new radix tree entry. - * - * The PMD path doesn't have an equivalent to - * dax_pfn_mkwrite(), though, so for a read followed by a - * write we traverse all the way through dax_pmd_fault() - * twice. This means we can just skip inserting a radix tree - * entry completely on the initial read and just wait until - * the write to insert a dirty entry. - */ - if (write) { - /* - * We should insert radix-tree entry and dirty it here. - * For now this is broken... - */ - } - - dev_dbg(part_to_dev(bdev->bd_part), - "%s: %s addr: %lx pfn: %lx sect: %llx\n", - __func__, current->comm, address, - pfn_t_to_pfn(dax.pfn), - (unsigned long long) dax.sector); - result |= vmf_insert_pfn_pmd(vma, address, pmd, - dax.pfn, write); - } - - out: - return result; - - fallback: - count_vm_event(THP_FAULT_FALLBACK); - result = VM_FAULT_FALLBACK; - goto out; -} -EXPORT_SYMBOL_GPL(dax_pmd_fault); -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ - /** * dax_pfn_mkwrite - handle first write to DAX page * @vma: The virtual memory area where the fault occurred diff --git a/include/linux/dax.h b/include/linux/dax.h index a41a747d6112..0f74866edae6 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -48,16 +48,12 @@ static inline int __dax_zero_page_range(struct block_device *bdev, } #endif -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) -int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *, - unsigned int flags, get_block_t); -#else static inline int dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, unsigned int flags, get_block_t gb) { return VM_FAULT_FALLBACK; } -#endif + int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *); #define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb) -- cgit v1.2.3 From 11c59c92f44d9272db7655a462608658a6d95013 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Tue, 8 Nov 2016 11:32:46 +1100 Subject: dax: correct dax iomap code namespace The recently added DAX functions that use the new struct iomap data structure were named iomap_dax_rw(), iomap_dax_fault() and iomap_dax_actor(). These are actually defined in fs/dax.c, though, so should be part of the "dax" namespace and not the "iomap" namespace. Rename them to dax_iomap_rw(), dax_iomap_fault() and dax_iomap_actor() respectively. Signed-off-by: Ross Zwisler Suggested-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Dave Chinner --- fs/dax.c | 16 ++++++++-------- fs/ext2/file.c | 6 +++--- fs/xfs/xfs_file.c | 8 ++++---- include/linux/dax.h | 4 ++-- 4 files changed, 17 insertions(+), 17 deletions(-) (limited to 'include/linux') diff --git a/fs/dax.c b/fs/dax.c index 3d0b1032c555..fdbd7a1ec6cf 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1031,7 +1031,7 @@ EXPORT_SYMBOL_GPL(dax_truncate_page); #ifdef CONFIG_FS_IOMAP static loff_t -iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, +dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct iov_iter *iter = data; @@ -1088,7 +1088,7 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, } /** - * iomap_dax_rw - Perform I/O to a DAX file + * dax_iomap_rw - Perform I/O to a DAX file * @iocb: The control block for this I/O * @iter: The addresses to do I/O from or to * @ops: iomap ops passed from the file system @@ -1098,7 +1098,7 @@ iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data, * and evicting any page cache pages in the region under I/O. */ ssize_t -iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, +dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops) { struct address_space *mapping = iocb->ki_filp->f_mapping; @@ -1128,7 +1128,7 @@ iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, while (iov_iter_count(iter)) { ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops, - iter, iomap_dax_actor); + iter, dax_iomap_actor); if (ret <= 0) break; pos += ret; @@ -1138,10 +1138,10 @@ iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, iocb->ki_pos += done; return done ? done : ret; } -EXPORT_SYMBOL_GPL(iomap_dax_rw); +EXPORT_SYMBOL_GPL(dax_iomap_rw); /** - * iomap_dax_fault - handle a page fault on a DAX file + * dax_iomap_fault - handle a page fault on a DAX file * @vma: The virtual memory area where the fault occurred * @vmf: The description of the fault * @ops: iomap ops passed from the file system @@ -1150,7 +1150,7 @@ EXPORT_SYMBOL_GPL(iomap_dax_rw); * or mkwrite handler for DAX files. Assumes the caller has done all the * necessary locking for the page fault to proceed successfully. */ -int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, +int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, struct iomap_ops *ops) { struct address_space *mapping = vma->vm_file->f_mapping; @@ -1252,5 +1252,5 @@ int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, return VM_FAULT_SIGBUS | major; return VM_FAULT_NOPAGE | major; } -EXPORT_SYMBOL_GPL(iomap_dax_fault); +EXPORT_SYMBOL_GPL(dax_iomap_fault); #endif /* CONFIG_FS_IOMAP */ diff --git a/fs/ext2/file.c b/fs/ext2/file.c index fb88b51ca947..b0f241528a30 100644 --- a/fs/ext2/file.c +++ b/fs/ext2/file.c @@ -38,7 +38,7 @@ static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) return 0; /* skip atime */ inode_lock_shared(inode); - ret = iomap_dax_rw(iocb, to, &ext2_iomap_ops); + ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops); inode_unlock_shared(inode); file_accessed(iocb->ki_filp); @@ -62,7 +62,7 @@ static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret) goto out_unlock; - ret = iomap_dax_rw(iocb, from, &ext2_iomap_ops); + ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops); if (ret > 0 && iocb->ki_pos > i_size_read(inode)) { i_size_write(inode, iocb->ki_pos); mark_inode_dirty(inode); @@ -99,7 +99,7 @@ static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) } down_read(&ei->dax_sem); - ret = iomap_dax_fault(vma, vmf, &ext2_iomap_ops); + ret = dax_iomap_fault(vma, vmf, &ext2_iomap_ops); up_read(&ei->dax_sem); if (vmf->flags & FAULT_FLAG_WRITE) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index a314fc7b56fa..e7f35d548cfc 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -344,7 +344,7 @@ xfs_file_dax_read( return 0; /* skip atime */ xfs_rw_ilock(ip, XFS_IOLOCK_SHARED); - ret = iomap_dax_rw(iocb, to, &xfs_iomap_ops); + ret = dax_iomap_rw(iocb, to, &xfs_iomap_ops); xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED); file_accessed(iocb->ki_filp); @@ -691,7 +691,7 @@ xfs_file_dax_write( trace_xfs_file_dax_write(ip, count, pos); - ret = iomap_dax_rw(iocb, from, &xfs_iomap_ops); + ret = dax_iomap_rw(iocb, from, &xfs_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); @@ -1640,7 +1640,7 @@ xfs_filemap_page_mkwrite( xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); if (IS_DAX(inode)) { - ret = iomap_dax_fault(vma, vmf, &xfs_iomap_ops); + ret = dax_iomap_fault(vma, vmf, &xfs_iomap_ops); } else { ret = iomap_page_mkwrite(vma, vmf, &xfs_iomap_ops); ret = block_page_mkwrite_return(ret); @@ -1674,7 +1674,7 @@ xfs_filemap_fault( * changes to xfs_get_blocks_direct() to map unwritten extent * ioend for conversion on read-only mappings. */ - ret = iomap_dax_fault(vma, vmf, &xfs_iomap_ops); + ret = dax_iomap_fault(vma, vmf, &xfs_iomap_ops); } else ret = filemap_fault(vma, vmf); xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED); diff --git a/include/linux/dax.h b/include/linux/dax.h index 0f74866edae6..a3dfee4cb03f 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -11,13 +11,13 @@ struct iomap_ops; /* We use lowest available exceptional entry bit for locking */ #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) -ssize_t iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter, +ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops); ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *, get_block_t, dio_iodone_t, int flags); int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t); int dax_truncate_page(struct inode *, loff_t from, get_block_t); -int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, +int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, struct iomap_ops *ops); int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index); -- cgit v1.2.3 From fa28f7296a7ce38ed15dc06bd2149e04c8db9d4b Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Tue, 8 Nov 2016 11:33:35 +1100 Subject: dax: move RADIX_DAX_* defines to dax.h The RADIX_DAX_* defines currently mostly live in fs/dax.c, with just RADIX_DAX_ENTRY_LOCK being in include/linux/dax.h so it can be used in mm/filemap.c. When we add PMD support, though, mm/filemap.c will also need access to the RADIX_DAX_PTE type so it can properly construct a 4k sized empty entry. Instead of shifting the defines between dax.c and dax.h as they are individually used in other code, just move them wholesale to dax.h so they'll be available when we need them. Signed-off-by: Ross Zwisler Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Dave Chinner --- fs/dax.c | 14 -------------- include/linux/dax.h | 15 ++++++++++++++- 2 files changed, 14 insertions(+), 15 deletions(-) (limited to 'include/linux') diff --git a/fs/dax.c b/fs/dax.c index 6edd89b3b69c..c45cc4d8e996 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -34,20 +34,6 @@ #include #include "internal.h" -/* - * We use lowest available bit in exceptional entry for locking, other two - * bits to determine entry type. In total 3 special bits. - */ -#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3) -#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) -#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) -#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD) -#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK) -#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) -#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ - RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \ - RADIX_TREE_EXCEPTIONAL_ENTRY)) - /* We choose 4096 entries - same as per-zone page wait tables */ #define DAX_WAIT_TABLE_BITS 12 #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS) diff --git a/include/linux/dax.h b/include/linux/dax.h index a3dfee4cb03f..e9ea78c1cf98 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -8,8 +8,21 @@ struct iomap_ops; -/* We use lowest available exceptional entry bit for locking */ +/* + * We use lowest available bit in exceptional entry for locking, other two + * bits to determine entry type. In total 3 special bits. + */ +#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3) #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) +#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) +#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) +#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD) +#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK) +#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) +#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ + RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \ + RADIX_TREE_EXCEPTIONAL_ENTRY)) + ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops); -- cgit v1.2.3 From 642261ac995e01d7837db1f4b90181496f7e6835 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Tue, 8 Nov 2016 11:34:45 +1100 Subject: dax: add struct iomap based DAX PMD support DAX PMDs have been disabled since Jan Kara introduced DAX radix tree based locking. This patch allows DAX PMDs to participate in the DAX radix tree based locking scheme so that they can be re-enabled using the new struct iomap based fault handlers. There are currently three types of DAX 4k entries: 4k zero pages, 4k DAX mappings that have an associated block allocation, and 4k DAX empty entries. The empty entries exist to provide locking for the duration of a given page fault. This patch adds three equivalent 2MiB DAX entries: Huge Zero Page (HZP) entries, PMD DAX entries that have associated block allocations, and 2 MiB DAX empty entries. Unlike the 4k case where we insert a struct page* into the radix tree for 4k zero pages, for HZP we insert a DAX exceptional entry with the new RADIX_DAX_HZP flag set. This is because we use a single 2 MiB zero page in every 2MiB hole mapping, and it doesn't make sense to have that same struct page* with multiple entries in multiple trees. This would cause contention on the single page lock for the one Huge Zero Page, and it would break the page->index and page->mapping associations that are assumed to be valid in many other places in the kernel. One difficult use case is when one thread is trying to use 4k entries in radix tree for a given offset, and another thread is using 2 MiB entries for that same offset. The current code handles this by making the 2 MiB user fall back to 4k entries for most cases. This was done because it is the simplest solution, and because the use of 2MiB pages is already opportunistic. If we were to try to upgrade from 4k pages to 2MiB pages for a given range, we run into the problem of how we lock out 4k page faults for the entire 2MiB range while we clean out the radix tree so we can insert the 2MiB entry. We can solve this problem if we need to, but I think that the cases where both 2MiB entries and 4K entries are being used for the same range will be rare enough and the gain small enough that it probably won't be worth the complexity. Signed-off-by: Ross Zwisler Reviewed-by: Jan Kara Signed-off-by: Dave Chinner --- fs/dax.c | 378 +++++++++++++++++++++++++++++++++++++++++++++++----- include/linux/dax.h | 55 ++++++-- mm/filemap.c | 3 +- 3 files changed, 386 insertions(+), 50 deletions(-) (limited to 'include/linux') diff --git a/fs/dax.c b/fs/dax.c index 0582c7c2ae40..281e91a63367 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -76,6 +76,26 @@ static void dax_unmap_atomic(struct block_device *bdev, blk_queue_exit(bdev->bd_queue); } +static int dax_is_pmd_entry(void *entry) +{ + return (unsigned long)entry & RADIX_DAX_PMD; +} + +static int dax_is_pte_entry(void *entry) +{ + return !((unsigned long)entry & RADIX_DAX_PMD); +} + +static int dax_is_zero_entry(void *entry) +{ + return (unsigned long)entry & RADIX_DAX_HZP; +} + +static int dax_is_empty_entry(void *entry) +{ + return (unsigned long)entry & RADIX_DAX_EMPTY; +} + struct page *read_dax_sector(struct block_device *bdev, sector_t n) { struct page *page = alloc_pages(GFP_KERNEL, 0); @@ -281,7 +301,7 @@ static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping, * queue to the start of that PMD. This ensures that all offsets in * the range covered by the PMD map to the same bit lock. */ - if (RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) + if (dax_is_pmd_entry(entry)) index &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1); key->mapping = mapping; @@ -413,36 +433,116 @@ static void put_unlocked_mapping_entry(struct address_space *mapping, * radix tree entry locked. If the radix tree doesn't contain given index, * create empty exceptional entry for the index and return with it locked. * + * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will + * either return that locked entry or will return an error. This error will + * happen if there are any 4k entries (either zero pages or DAX entries) + * within the 2MiB range that we are requesting. + * + * We always favor 4k entries over 2MiB entries. There isn't a flow where we + * evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB + * insertion will fail if it finds any 4k entries already in the tree, and a + * 4k insertion will cause an existing 2MiB entry to be unmapped and + * downgraded to 4k entries. This happens for both 2MiB huge zero pages as + * well as 2MiB empty entries. + * + * The exception to this downgrade path is for 2MiB DAX PMD entries that have + * real storage backing them. We will leave these real 2MiB DAX entries in + * the tree, and PTE writes will simply dirty the entire 2MiB DAX entry. + * * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For * persistent memory the benefit is doubtful. We can add that later if we can * show it helps. */ -static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index) +static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, + unsigned long size_flag) { + bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */ void *entry, **slot; restart: spin_lock_irq(&mapping->tree_lock); entry = get_unlocked_mapping_entry(mapping, index, &slot); + + if (entry) { + if (size_flag & RADIX_DAX_PMD) { + if (!radix_tree_exceptional_entry(entry) || + dax_is_pte_entry(entry)) { + put_unlocked_mapping_entry(mapping, index, + entry); + entry = ERR_PTR(-EEXIST); + goto out_unlock; + } + } else { /* trying to grab a PTE entry */ + if (radix_tree_exceptional_entry(entry) && + dax_is_pmd_entry(entry) && + (dax_is_zero_entry(entry) || + dax_is_empty_entry(entry))) { + pmd_downgrade = true; + } + } + } + /* No entry for given index? Make sure radix tree is big enough. */ - if (!entry) { + if (!entry || pmd_downgrade) { int err; + if (pmd_downgrade) { + /* + * Make sure 'entry' remains valid while we drop + * mapping->tree_lock. + */ + entry = lock_slot(mapping, slot); + } + spin_unlock_irq(&mapping->tree_lock); err = radix_tree_preload( mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM); - if (err) + if (err) { + if (pmd_downgrade) + put_locked_mapping_entry(mapping, index, entry); return ERR_PTR(err); - entry = (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | - RADIX_DAX_ENTRY_LOCK); + } + + /* + * Besides huge zero pages the only other thing that gets + * downgraded are empty entries which don't need to be + * unmapped. + */ + if (pmd_downgrade && dax_is_zero_entry(entry)) + unmap_mapping_range(mapping, + (index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); + spin_lock_irq(&mapping->tree_lock); - err = radix_tree_insert(&mapping->page_tree, index, entry); + + if (pmd_downgrade) { + radix_tree_delete(&mapping->page_tree, index); + mapping->nrexceptional--; + dax_wake_mapping_entry_waiter(mapping, index, entry, + true); + } + + entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY); + + err = __radix_tree_insert(&mapping->page_tree, index, + dax_radix_order(entry), entry); radix_tree_preload_end(); if (err) { spin_unlock_irq(&mapping->tree_lock); - /* Someone already created the entry? */ - if (err == -EEXIST) + /* + * Someone already created the entry? This is a + * normal failure when inserting PMDs in a range + * that already contains PTEs. In that case we want + * to return -EEXIST immediately. + */ + if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD)) goto restart; + /* + * Our insertion of a DAX PMD entry failed, most + * likely because it collided with a PTE sized entry + * at a different index in the PMD range. We haven't + * inserted anything into the radix tree and have no + * waiters to wake. + */ return ERR_PTR(err); } /* Good, we have inserted empty locked entry into the tree. */ @@ -466,6 +566,7 @@ restart: return page; } entry = lock_slot(mapping, slot); + out_unlock: spin_unlock_irq(&mapping->tree_lock); return entry; } @@ -473,9 +574,9 @@ restart: /* * We do not necessarily hold the mapping->tree_lock when we call this * function so it is possible that 'entry' is no longer a valid item in the - * radix tree. This is okay, though, because all we really need to do is to - * find the correct waitqueue where tasks might be sleeping waiting for that - * old 'entry' and wake them. + * radix tree. This is okay because all we really need to do is to find the + * correct waitqueue where tasks might be waiting for that old 'entry' and + * wake them. */ void dax_wake_mapping_entry_waiter(struct address_space *mapping, pgoff_t index, void *entry, bool wake_all) @@ -588,11 +689,17 @@ static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size return 0; } -#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_SHIFT)) - +/* + * By this point grab_mapping_entry() has ensured that we have a locked entry + * of the appropriate size so we don't have to worry about downgrading PMDs to + * PTEs. If we happen to be trying to insert a PTE and there is a PMD + * already in the tree, we will skip the insertion and just dirty the PMD as + * appropriate. + */ static void *dax_insert_mapping_entry(struct address_space *mapping, struct vm_fault *vmf, - void *entry, sector_t sector) + void *entry, sector_t sector, + unsigned long flags) { struct radix_tree_root *page_tree = &mapping->page_tree; int error = 0; @@ -615,22 +722,35 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM); if (error) return ERR_PTR(error); + } else if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_HZP)) { + /* replacing huge zero page with PMD block mapping */ + unmap_mapping_range(mapping, + (vmf->pgoff << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0); } spin_lock_irq(&mapping->tree_lock); - new_entry = (void *)((unsigned long)RADIX_DAX_ENTRY(sector, false) | - RADIX_DAX_ENTRY_LOCK); + new_entry = dax_radix_locked_entry(sector, flags); + if (hole_fill) { __delete_from_page_cache(entry, NULL); /* Drop pagecache reference */ put_page(entry); - error = radix_tree_insert(page_tree, index, new_entry); + error = __radix_tree_insert(page_tree, index, + dax_radix_order(new_entry), new_entry); if (error) { new_entry = ERR_PTR(error); goto unlock; } mapping->nrexceptional++; - } else { + } else if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { + /* + * Only swap our new entry into the radix tree if the current + * entry is a zero page or an empty entry. If a normal PTE or + * PMD entry is already in the tree, we leave it alone. This + * means that if we are trying to insert a PTE and the + * existing entry is a PMD, we will just leave the PMD in the + * tree and dirty it if necessary. + */ void **slot; void *ret; @@ -660,7 +780,6 @@ static int dax_writeback_one(struct block_device *bdev, struct address_space *mapping, pgoff_t index, void *entry) { struct radix_tree_root *page_tree = &mapping->page_tree; - int type = RADIX_DAX_TYPE(entry); struct radix_tree_node *node; struct blk_dax_ctl dax; void **slot; @@ -681,13 +800,21 @@ static int dax_writeback_one(struct block_device *bdev, if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) goto unlock; - if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { + if (WARN_ON_ONCE(dax_is_empty_entry(entry) || + dax_is_zero_entry(entry))) { ret = -EIO; goto unlock; } - dax.sector = RADIX_DAX_SECTOR(entry); - dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE); + /* + * Even if dax_writeback_mapping_range() was given a wbc->range_start + * in the middle of a PMD, the 'index' we are given will be aligned to + * the start index of the PMD, as will the sector we pull from + * 'entry'. This allows us to flush for PMD_SIZE and not have to + * worry about partial PMD writebacks. + */ + dax.sector = dax_radix_sector(entry); + dax.size = PAGE_SIZE << dax_radix_order(entry); spin_unlock_irq(&mapping->tree_lock); /* @@ -726,12 +853,11 @@ int dax_writeback_mapping_range(struct address_space *mapping, struct block_device *bdev, struct writeback_control *wbc) { struct inode *inode = mapping->host; - pgoff_t start_index, end_index, pmd_index; + pgoff_t start_index, end_index; pgoff_t indices[PAGEVEC_SIZE]; struct pagevec pvec; bool done = false; int i, ret = 0; - void *entry; if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) return -EIO; @@ -741,15 +867,6 @@ int dax_writeback_mapping_range(struct address_space *mapping, start_index = wbc->range_start >> PAGE_SHIFT; end_index = wbc->range_end >> PAGE_SHIFT; - pmd_index = DAX_PMD_INDEX(start_index); - - rcu_read_lock(); - entry = radix_tree_lookup(&mapping->page_tree, pmd_index); - rcu_read_unlock(); - - /* see if the start of our range is covered by a PMD entry */ - if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) - start_index = pmd_index; tag_pages_for_writeback(mapping, start_index, end_index); @@ -794,7 +911,7 @@ static int dax_insert_mapping(struct address_space *mapping, return PTR_ERR(dax.addr); dax_unmap_atomic(bdev, &dax); - ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector); + ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0); if (IS_ERR(ret)) return PTR_ERR(ret); *entryp = ret; @@ -841,7 +958,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, bh.b_bdev = inode->i_sb->s_bdev; bh.b_size = PAGE_SIZE; - entry = grab_mapping_entry(mapping, vmf->pgoff); + entry = grab_mapping_entry(mapping, vmf->pgoff, 0); if (IS_ERR(entry)) { error = PTR_ERR(entry); goto out; @@ -1162,7 +1279,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, if (pos >= i_size_read(inode)) return VM_FAULT_SIGBUS; - entry = grab_mapping_entry(mapping, vmf->pgoff); + entry = grab_mapping_entry(mapping, vmf->pgoff, 0); if (IS_ERR(entry)) { error = PTR_ERR(entry); goto out; @@ -1264,4 +1381,191 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, return VM_FAULT_NOPAGE | major; } EXPORT_SYMBOL_GPL(dax_iomap_fault); + +#ifdef CONFIG_FS_DAX_PMD +/* + * The 'colour' (ie low bits) within a PMD of a page offset. This comes up + * more often than one might expect in the below functions. + */ +#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) + +static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd, + struct vm_fault *vmf, unsigned long address, + struct iomap *iomap, loff_t pos, bool write, void **entryp) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + struct block_device *bdev = iomap->bdev; + struct blk_dax_ctl dax = { + .sector = dax_iomap_sector(iomap, pos), + .size = PMD_SIZE, + }; + long length = dax_map_atomic(bdev, &dax); + void *ret; + + if (length < 0) /* dax_map_atomic() failed */ + return VM_FAULT_FALLBACK; + if (length < PMD_SIZE) + goto unmap_fallback; + if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) + goto unmap_fallback; + if (!pfn_t_devmap(dax.pfn)) + goto unmap_fallback; + + dax_unmap_atomic(bdev, &dax); + + ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector, + RADIX_DAX_PMD); + if (IS_ERR(ret)) + return VM_FAULT_FALLBACK; + *entryp = ret; + + return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write); + + unmap_fallback: + dax_unmap_atomic(bdev, &dax); + return VM_FAULT_FALLBACK; +} + +static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd, + struct vm_fault *vmf, unsigned long address, + struct iomap *iomap, void **entryp) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + unsigned long pmd_addr = address & PMD_MASK; + struct page *zero_page; + spinlock_t *ptl; + pmd_t pmd_entry; + void *ret; + + zero_page = mm_get_huge_zero_page(vma->vm_mm); + + if (unlikely(!zero_page)) + return VM_FAULT_FALLBACK; + + ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0, + RADIX_DAX_PMD | RADIX_DAX_HZP); + if (IS_ERR(ret)) + return VM_FAULT_FALLBACK; + *entryp = ret; + + ptl = pmd_lock(vma->vm_mm, pmd); + if (!pmd_none(*pmd)) { + spin_unlock(ptl); + return VM_FAULT_FALLBACK; + } + + pmd_entry = mk_pmd(zero_page, vma->vm_page_prot); + pmd_entry = pmd_mkhuge(pmd_entry); + set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry); + spin_unlock(ptl); + return VM_FAULT_NOPAGE; +} + +int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, unsigned int flags, struct iomap_ops *ops) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + unsigned long pmd_addr = address & PMD_MASK; + bool write = flags & FAULT_FLAG_WRITE; + unsigned int iomap_flags = write ? IOMAP_WRITE : 0; + struct inode *inode = mapping->host; + int result = VM_FAULT_FALLBACK; + struct iomap iomap = { 0 }; + pgoff_t max_pgoff, pgoff; + struct vm_fault vmf; + void *entry; + loff_t pos; + int error; + + /* Fall back to PTEs if we're going to COW */ + if (write && !(vma->vm_flags & VM_SHARED)) + goto fallback; + + /* If the PMD would extend outside the VMA */ + if (pmd_addr < vma->vm_start) + goto fallback; + if ((pmd_addr + PMD_SIZE) > vma->vm_end) + goto fallback; + + /* + * Check whether offset isn't beyond end of file now. Caller is + * supposed to hold locks serializing us with truncate / punch hole so + * this is a reliable test. + */ + pgoff = linear_page_index(vma, pmd_addr); + max_pgoff = (i_size_read(inode) - 1) >> PAGE_SHIFT; + + if (pgoff > max_pgoff) + return VM_FAULT_SIGBUS; + + /* If the PMD would extend beyond the file size */ + if ((pgoff | PG_PMD_COLOUR) > max_pgoff) + goto fallback; + + /* + * grab_mapping_entry() will make sure we get a 2M empty entry, a DAX + * PMD or a HZP entry. If it can't (because a 4k page is already in + * the tree, for instance), it will return -EEXIST and we just fall + * back to 4k entries. + */ + entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD); + if (IS_ERR(entry)) + goto fallback; + + /* + * Note that we don't use iomap_apply here. We aren't doing I/O, only + * setting up a mapping, so really we're using iomap_begin() as a way + * to look up our filesystem block. + */ + pos = (loff_t)pgoff << PAGE_SHIFT; + error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap); + if (error) + goto unlock_entry; + if (iomap.offset + iomap.length < pos + PMD_SIZE) + goto finish_iomap; + + vmf.pgoff = pgoff; + vmf.flags = flags; + vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO; + + switch (iomap.type) { + case IOMAP_MAPPED: + result = dax_pmd_insert_mapping(vma, pmd, &vmf, address, + &iomap, pos, write, &entry); + break; + case IOMAP_UNWRITTEN: + case IOMAP_HOLE: + if (WARN_ON_ONCE(write)) + goto finish_iomap; + result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap, + &entry); + break; + default: + WARN_ON_ONCE(1); + break; + } + + finish_iomap: + if (ops->iomap_end) { + if (result == VM_FAULT_FALLBACK) { + ops->iomap_end(inode, pos, PMD_SIZE, 0, iomap_flags, + &iomap); + } else { + error = ops->iomap_end(inode, pos, PMD_SIZE, PMD_SIZE, + iomap_flags, &iomap); + if (error) + result = VM_FAULT_FALLBACK; + } + } + unlock_entry: + put_locked_mapping_entry(mapping, pgoff, entry); + fallback: + if (result == VM_FAULT_FALLBACK) { + split_huge_pmd(vma, pmd, address); + count_vm_event(THP_FAULT_FALLBACK); + } + return result; +} +EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault); +#endif /* CONFIG_FS_DAX_PMD */ #endif /* CONFIG_FS_IOMAP */ diff --git a/include/linux/dax.h b/include/linux/dax.h index e9ea78c1cf98..8d1a5c47945f 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -9,20 +9,32 @@ struct iomap_ops; /* - * We use lowest available bit in exceptional entry for locking, other two - * bits to determine entry type. In total 3 special bits. + * We use lowest available bit in exceptional entry for locking, one bit for + * the entry size (PMD) and two more to tell us if the entry is a huge zero + * page (HZP) or an empty entry that is just used for locking. In total four + * special bits. + * + * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the HZP and + * EMPTY bits aren't set the entry is a normal DAX entry with a filesystem + * block allocation. */ -#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3) +#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4) #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) -#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) -#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) -#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD) -#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK) -#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT)) -#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \ - RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \ - RADIX_TREE_EXCEPTIONAL_ENTRY)) +#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1)) +#define RADIX_DAX_HZP (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2)) +#define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3)) +static inline unsigned long dax_radix_sector(void *entry) +{ + return (unsigned long)entry >> RADIX_DAX_SHIFT; +} + +static inline void *dax_radix_locked_entry(sector_t sector, unsigned long flags) +{ + return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags | + ((unsigned long)sector << RADIX_DAX_SHIFT) | + RADIX_DAX_ENTRY_LOCK); +} ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, struct iomap_ops *ops); @@ -67,6 +79,27 @@ static inline int dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, return VM_FAULT_FALLBACK; } +#ifdef CONFIG_FS_DAX_PMD +static inline unsigned int dax_radix_order(void *entry) +{ + if ((unsigned long)entry & RADIX_DAX_PMD) + return PMD_SHIFT - PAGE_SHIFT; + return 0; +} +int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, unsigned int flags, struct iomap_ops *ops); +#else +static inline unsigned int dax_radix_order(void *entry) +{ + return 0; +} +static inline int dax_iomap_pmd_fault(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmd, unsigned int flags, + struct iomap_ops *ops) +{ + return VM_FAULT_FALLBACK; +} +#endif int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *); #define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb) diff --git a/mm/filemap.c b/mm/filemap.c index 1ffb7dcd1b5d..00ab94a882de 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -137,8 +137,7 @@ static int page_cache_tree_insert(struct address_space *mapping, } else { /* DAX can replace empty locked entry with a hole */ WARN_ON_ONCE(p != - (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | - RADIX_DAX_ENTRY_LOCK)); + dax_radix_locked_entry(0, RADIX_DAX_EMPTY)); /* DAX accounts exceptional entries as normal pages */ if (node) workingset_node_pages_dec(node); -- cgit v1.2.3 From 9484ab1bf4464faae695321dd4fa66365beda74e Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 10 Nov 2016 10:26:50 +1100 Subject: dax: Introduce IOMAP_FAULT flag Introduce a flag telling iomap operations whether they are handling a fault or other IO. That may influence behavior wrt inode size and similar things. Signed-off-by: Jan Kara Reviewed-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Dave Chinner --- fs/dax.c | 4 ++-- fs/iomap.c | 5 +++-- include/linux/iomap.h | 1 + 3 files changed, 6 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/fs/dax.c b/fs/dax.c index 281e91a63367..28af41b9da3a 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1266,7 +1266,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf, loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; sector_t sector; struct iomap iomap = { 0 }; - unsigned flags = 0; + unsigned flags = IOMAP_FAULT; int error, major = 0; int locked_status = 0; void *entry; @@ -1467,7 +1467,7 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, struct address_space *mapping = vma->vm_file->f_mapping; unsigned long pmd_addr = address & PMD_MASK; bool write = flags & FAULT_FLAG_WRITE; - unsigned int iomap_flags = write ? IOMAP_WRITE : 0; + unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; struct inode *inode = mapping->host; int result = VM_FAULT_FALLBACK; struct iomap iomap = { 0 }; diff --git a/fs/iomap.c b/fs/iomap.c index 013d1d36fbbf..51a02573405e 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -468,8 +468,9 @@ int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, offset = page_offset(page); while (length > 0) { - ret = iomap_apply(inode, offset, length, IOMAP_WRITE, - ops, page, iomap_page_mkwrite_actor); + ret = iomap_apply(inode, offset, length, + IOMAP_WRITE | IOMAP_FAULT, ops, page, + iomap_page_mkwrite_actor); if (unlikely(ret <= 0)) goto out_unlock; offset += ret; diff --git a/include/linux/iomap.h b/include/linux/iomap.h index e63e288dee83..b9e7b8ec8c1d 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -44,6 +44,7 @@ struct iomap { */ #define IOMAP_WRITE (1 << 0) #define IOMAP_ZERO (1 << 1) +#define IOMAP_FAULT (1 << 3) /* mapping for page fault */ struct iomap_ops { /* -- cgit v1.2.3