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Commit e2ae766c authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
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ext4: convert DAX faults to iomap infrastructure 



Convert DAX faults to use iomap infrastructure. We would not have to start
transaction in ext4_dax_fault() anymore since ext4_iomap_begin takes
care of that but so far we do that to avoid lock inversion of
transaction start with DAX entry lock which gets acquired in
dax_iomap_fault() before calling ->iomap_begin handler.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 96f8ba3d

fs/ext4/file.c

+5 −4
Original line number Diff line number Diff line
@@ -275,7 +275,7 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	if (IS_ERR(handle))

		result = VM_FAULT_SIGBUS;

	else

		result = dax_fault(vma, vmf, ext4_dax_get_block);

		result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);



	if (write) {

		if (!IS_ERR(handle))
@@ -309,9 +309,10 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, 


	if (IS_ERR(handle))

		result = VM_FAULT_SIGBUS;

	else

		result = dax_pmd_fault(vma, addr, pmd, flags,

					 ext4_dax_get_block);

	else {

		result = dax_iomap_pmd_fault(vma, addr, pmd, flags,

					     &ext4_iomap_ops);

	}



	if (write) {

		if (!IS_ERR(handle))

fs/ext4/inode.c

+9 −5
Original line number Diff line number Diff line
@@ -3369,12 +3369,16 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, 
		}



		/*

		 * If we added blocks beyond i_size we need to make sure they

		 * If we added blocks beyond i_size, we need to make sure they

		 * will get truncated if we crash before updating i_size in

		 * ext4_iomap_end().

		 */

		if (first_block + map.m_len >

		    (inode->i_size + (1 << blkbits) - 1) >> blkbits) {

		 * ext4_iomap_end(). For faults we don't need to do that (and

		 * even cannot because for orphan list operations inode_lock is

		 * required) - if we happen to instantiate block beyond i_size,

		 * it is because we race with truncate which has already added

		 * the inode to the orphan list.

		 */

		if (!(flags & IOMAP_FAULT) && first_block + map.m_len >

		    (i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {

			int err;



			err = ext4_orphan_add(handle, inode);
@@ -3420,7 +3424,7 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length, 
	int blkbits = inode->i_blkbits;

	bool truncate = false;



	if (!(flags & IOMAP_WRITE))

	if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))

		return 0;



	handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);