Commit 22446423 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

ext4: fix ENOSPC handling in DAX page fault handler 



When allocation of underlying block for a page fault fails, we fail the
fault with SIGBUS. However we may well hit ENOSPC just due to lots of
free blocks being held by the running / committing transaction. So
propagate the error from ext4_iomap_begin() and implement do standard
allocation retry loop in ext4_dax_huge_fault().

Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent c0b24625

fs/ext4/file.c

+8 −2
Original line number Diff line number Diff line
@@ -280,7 +280,8 @@ out: 
static int ext4_dax_huge_fault(struct vm_fault *vmf,

		enum page_entry_size pe_size)

{

	int result;

	int result, error = 0;

	int retries = 0;

	handle_t *handle = NULL;

	struct inode *inode = file_inode(vmf->vma->vm_file);

	struct super_block *sb = inode->i_sb;
@@ -304,6 +305,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, 
		sb_start_pagefault(sb);

		file_update_time(vmf->vma->vm_file);

		down_read(&EXT4_I(inode)->i_mmap_sem);

retry:

		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,

					       EXT4_DATA_TRANS_BLOCKS(sb));

		if (IS_ERR(handle)) {
@@ -314,9 +316,13 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, 
	} else {

		down_read(&EXT4_I(inode)->i_mmap_sem);

	}

	result = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &ext4_iomap_ops);

	result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);

	if (write) {

		ext4_journal_stop(handle);



		if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&

		    ext4_should_retry_alloc(sb, &retries))

			goto retry;

		/* Handling synchronous page fault? */

		if (result & VM_FAULT_NEEDDSYNC)

			result = dax_finish_sync_fault(vmf, pe_size, pfn);

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