From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f67.google.com ([209.85.215.67]:43024 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751851AbeFFOJ4 (ORCPT ); Wed, 6 Jun 2018 10:09:56 -0400 MIME-Version: 1.0 In-Reply-To: <20180606132228.GF3539@twin.jikos.cz> References: <20180605154635.GA27201@jordon-HP-15-Notebook-PC> <20180606132228.GF3539@twin.jikos.cz> From: Souptick Joarder Date: Wed, 6 Jun 2018 19:39:53 +0530 Message-ID: Subject: Re: [PATCH] fs: btrfs: Change return type to vm_fault_t To: dsterba@suse.cz, Souptick Joarder , Matthew Wilcox , Chris Mason , jbacik@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Jun 6, 2018 at 6:52 PM, David Sterba wrote: > On Tue, Jun 05, 2018 at 09:16:35PM +0530, Souptick Joarder wrote: >> Use new return type vm_fault_t for fault handler. For >> now, this is just documenting that the function returns >> a VM_FAULT value rather than an errno. Once all instances >> are converted, vm_fault_t will become a distinct type. >> >> Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t") >> >> vmf_error() is the newly introduce inline function >> in 4.17-rc6. >> >> Signed-off-by: Souptick Joarder >> --- >> fs/btrfs/ctree.h | 2 +- >> fs/btrfs/inode.c | 28 +++++++++++++--------------- >> 2 files changed, 14 insertions(+), 16 deletions(-) >> >> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h >> index 0d422c9..1f52d9fd 100644 >> --- a/fs/btrfs/ctree.h >> +++ b/fs/btrfs/ctree.h >> @@ -3218,7 +3218,7 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset, >> size_t size, struct bio *bio, >> unsigned long bio_flags); >> void btrfs_set_range_writeback(void *private_data, u64 start, u64 end); >> -int btrfs_page_mkwrite(struct vm_fault *vmf); >> +vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf); >> int btrfs_readpage(struct file *file, struct page *page); >> void btrfs_evict_inode(struct inode *inode); >> int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc); >> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >> index 0b86cf1..20bde86 100644 >> --- a/fs/btrfs/inode.c >> +++ b/fs/btrfs/inode.c >> @@ -8873,7 +8873,7 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset, >> * beyond EOF, then the page is guaranteed safe against truncation until we >> * unlock the page. >> */ >> -int btrfs_page_mkwrite(struct vm_fault *vmf) >> +vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) >> { >> struct page *page = vmf->page; >> struct inode *inode = file_inode(vmf->vma->vm_file); >> @@ -8885,8 +8885,9 @@ int btrfs_page_mkwrite(struct vm_fault *vmf) >> char *kaddr; >> unsigned long zero_start; >> loff_t size; >> - int ret; >> + int err; > > Please use ret2 for the variable name. We're leaving the err/ret naming > pattern and use 'ret' to match the function return value and ret2, ret3 > for the temporary return values. Is this new pattern specific to fs/btrfs file system ? > >> int reserved = 0; >> + vm_fault_t ret; >> u64 reserved_space; >> u64 page_start; >> u64 page_end; >> @@ -8907,17 +8908,14 @@ int btrfs_page_mkwrite(struct vm_fault *vmf) >> * end up waiting indefinitely to get a lock on the page currently >> * being processed by btrfs_page_mkwrite() function. >> */ >> - ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start, >> + err = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start, >> reserved_space); >> - if (!ret) { >> - ret = file_update_time(vmf->vma->vm_file); >> + if (!err) { >> + err = file_update_time(vmf->vma->vm_file); >> reserved = 1; >> } >> - if (ret) { >> - if (ret == -ENOMEM) >> - ret = VM_FAULT_OOM; >> - else /* -ENOSPC, -EIO, etc */ >> - ret = VM_FAULT_SIGBUS; >> + if (err) { >> + ret = vmf_error(err); >> if (reserved) >> goto out; >> goto out_noreserve; >> @@ -8976,15 +8974,15 @@ int btrfs_page_mkwrite(struct vm_fault *vmf) >> EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, >> 0, 0, &cached_state); >> >> - ret = btrfs_set_extent_delalloc(inode, page_start, end, 0, >> + err = btrfs_set_extent_delalloc(inode, page_start, end, 0, >> &cached_state, 0); >> - if (ret) { >> + if (err) { >> unlock_extent_cached(io_tree, page_start, page_end, >> &cached_state); >> ret = VM_FAULT_SIGBUS; >> goto out_unlock; >> } >> - ret = 0; >> + err = 0; >> >> /* page is wholly or partially inside EOF */ >> if (page_start + PAGE_SIZE > size) >> @@ -9009,11 +9007,11 @@ int btrfs_page_mkwrite(struct vm_fault *vmf) >> unlock_extent_cached(io_tree, page_start, page_end, &cached_state); >> >> out_unlock: >> - if (!ret) { >> + if (!err) { >> btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE, true); >> sb_end_pagefault(inode->i_sb); >> extent_changeset_free(data_reserved); >> - return VM_FAULT_LOCKED; >> + ret = VM_FAULT_LOCKED; > > That's not a direct change as it changes the code flow and lets the > branch continue. As the error handling and cleanup code is partially > done in this branch continuing wrong AFAICS. Sorry about it, I will correct and send v2. Is it possible to get it merge in 4.18 / 4.18-rc-X ?