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ext4: fix ENOSPC handling in DAX page fault handler

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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: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara 2018-01-07 16:41:01 -05:00 committed by Theodore Ts'o
parent c0b2462597
commit 2244642310
1 changed files with 8 additions and 2 deletions
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10
fs/ext4/file.c
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@ -280,7 +280,8 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
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);