From 430657b6be896db57d974375cc499ca212c7f01d Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Sun, 29 Jul 2018 17:00:22 -0400 Subject: [PATCH] ext4: handle layout changes to pinned DAX mappings Follow the lead of xfs_break_dax_layouts() and add synchronization between operations in ext4 which remove blocks from an inode (hole punch, truncate down, etc.) and pages which are pinned due to DAX DMA operations. Signed-off-by: Ross Zwisler Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Reviewed-by: Lukas Czerner --- fs/ext4/ext4.h | 1 + fs/ext4/extents.c | 17 +++++++++++++++++ fs/ext4/inode.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ fs/ext4/truncate.h | 4 ++++ 4 files changed, 68 insertions(+) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 6d7dec48372b..1fc013f3d944 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2459,6 +2459,7 @@ extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *); extern int ext4_inode_attach_jinode(struct inode *inode); extern int ext4_can_truncate(struct inode *inode); extern int ext4_truncate(struct inode *); +extern int ext4_break_layouts(struct inode *); extern int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length); extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks); extern void ext4_set_inode_flags(struct inode *); diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 8ce6fd5b10dd..72a361d5ef74 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4826,6 +4826,13 @@ static long ext4_zero_range(struct file *file, loff_t offset, * released from page cache. */ down_write(&EXT4_I(inode)->i_mmap_sem); + + ret = ext4_break_layouts(inode); + if (ret) { + up_write(&EXT4_I(inode)->i_mmap_sem); + goto out_mutex; + } + ret = ext4_update_disksize_before_punch(inode, offset, len); if (ret) { up_write(&EXT4_I(inode)->i_mmap_sem); @@ -5499,6 +5506,11 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len) * page cache. */ down_write(&EXT4_I(inode)->i_mmap_sem); + + ret = ext4_break_layouts(inode); + if (ret) + goto out_mmap; + /* * Need to round down offset to be aligned with page size boundary * for page size > block size. @@ -5647,6 +5659,11 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len) * page cache. */ down_write(&EXT4_I(inode)->i_mmap_sem); + + ret = ext4_break_layouts(inode); + if (ret) + goto out_mmap; + /* * Need to round down to align start offset to page size boundary * for page size > block size. diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index ba0de19fb1ad..60432498acfb 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4191,6 +4191,39 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, return 0; } +static void ext4_wait_dax_page(struct ext4_inode_info *ei, bool *did_unlock) +{ + *did_unlock = true; + up_write(&ei->i_mmap_sem); + schedule(); + down_write(&ei->i_mmap_sem); +} + +int ext4_break_layouts(struct inode *inode) +{ + struct ext4_inode_info *ei = EXT4_I(inode); + struct page *page; + bool retry; + int error; + + if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem))) + return -EINVAL; + + do { + retry = false; + page = dax_layout_busy_page(inode->i_mapping); + if (!page) + return 0; + + error = ___wait_var_event(&page->_refcount, + atomic_read(&page->_refcount) == 1, + TASK_INTERRUPTIBLE, 0, 0, + ext4_wait_dax_page(ei, &retry)); + } while (error == 0 && retry); + + return error; +} + /* * ext4_punch_hole: punches a hole in a file by releasing the blocks * associated with the given offset and length @@ -4264,6 +4297,11 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) * page cache. */ down_write(&EXT4_I(inode)->i_mmap_sem); + + ret = ext4_break_layouts(inode); + if (ret) + goto out_dio; + first_block_offset = round_up(offset, sb->s_blocksize); last_block_offset = round_down((offset + length), sb->s_blocksize) - 1; @@ -5553,6 +5591,14 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) ext4_wait_for_tail_page_commit(inode); } down_write(&EXT4_I(inode)->i_mmap_sem); + + rc = ext4_break_layouts(inode); + if (rc) { + up_write(&EXT4_I(inode)->i_mmap_sem); + error = rc; + goto err_out; + } + /* * Truncate pagecache after we've waited for commit * in data=journal mode to make pages freeable. diff --git a/fs/ext4/truncate.h b/fs/ext4/truncate.h index 0cb13badf473..bcbe3668c1d4 100644 --- a/fs/ext4/truncate.h +++ b/fs/ext4/truncate.h @@ -11,6 +11,10 @@ */ static inline void ext4_truncate_failed_write(struct inode *inode) { + /* + * We don't need to call ext4_break_layouts() because the blocks we + * are truncating were never visible to userspace. + */ down_write(&EXT4_I(inode)->i_mmap_sem); truncate_inode_pages(inode->i_mapping, inode->i_size); ext4_truncate(inode);