From: Jan Kara Subject: [PATCH 2/2] ext4: Fix ENOSPC handling in DAX page fault handler Date: Thu, 21 Dec 2017 17:30:55 +0100 Message-ID: <20171221163055.3943-3-jack@suse.cz> References: <20171221163055.3943-1-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Jan Kara , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ted Tso To: Return-path: In-Reply-To: <20171221163055.3943-1-jack-AlSwsSmVLrQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org 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(). Signed-off-by: Jan Kara --- fs/ext4/file.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) 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); -- 2.12.3