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[2/2] ext4: Fix ENOSPC handling in DAX page fault handler

Message ID 20180103100844.12787-3-jack@suse.cz
State Accepted, archived
Headers show
Series ext4: Fix ENOSPC handling for DAX faults | expand

Commit Message

Jan Kara Jan. 3, 2018, 10:08 a.m. UTC 
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>
---
 fs/ext4/file.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

Theodore Ts'o Jan. 7, 2018, 9:51 p.m. UTC | #1 
On Wed, Jan 03, 2018 at 11:08:44AM +0100, Jan Kara wrote:
> 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>

Applied, thanks.

					- Ted
diff mbox series

Patch

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1c7cd882d998..fb6f023622fe 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -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);