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ext4: handle layout changes to pinned DAX mappings

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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 <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
This commit is contained in:
Ross Zwisler 2018-07-29 17:00:22 -04:00 committed by Theodore Ts'o
parent cdbf8897cb
commit 430657b6be
4 changed files with 68 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
fs/ext4/ext4.h
View file

@ -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 *);

17
fs/ext4/extents.c
View file

@ -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.

46
fs/ext4/inode.c
View file

@ -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.

4
fs/ext4/truncate.h
View file

@ -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);