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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 9 Oct 2019 07:27:08 +0100 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x996R7l458917000 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 9 Oct 2019 06:27:07 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 471F04204B; Wed, 9 Oct 2019 06:27:07 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 694BF42049; Wed, 9 Oct 2019 06:27:05 +0000 (GMT) Received: from [9.199.159.72] (unknown [9.199.159.72]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 9 Oct 2019 06:27:05 +0000 (GMT) Subject: Re: [PATCH v4 5/8] ext4: move inode extension/truncate code out from ->iomap_end() callback To: Matthew Bobrowski , tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, david@fromorbit.com, darrick.wong@oracle.com References: From: Ritesh Harjani Date: Wed, 9 Oct 2019 11:57:04 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19100906-0028-0000-0000-000003A85700 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19100906-0029-0000-0000-0000246A5A07 Message-Id: <20191009062705.694BF42049@d06av24.portsmouth.uk.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-10-09_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=629 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910090058 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 10/3/19 5:04 PM, Matthew Bobrowski wrote: > In preparation for implementing the iomap direct I/O write path > modifications, the inode extension/truncate code needs to be moved out > from ext4_iomap_end(). For direct I/O, if the current code remained > within ext4_iomap_end() it would behave incorrectly. Updating the > inode size prior to converting unwritten extents to written extents > will potentially allow a racing direct I/O read operation to find > unwritten extents before they've been correctly converted. > > The inode extension/truncate code has been moved out into a new helper > ext4_handle_inode_extension(). This function has been designed so that > it can be used by both DAX and direct I/O paths. > > Signed-off-by: Matthew Bobrowski checkpatch shows some whitespaces error in your comments in this patch. But apart from that, patch looks good to me. You may add: Reviewed-by: Ritesh Harjani > --- > fs/ext4/file.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++- > fs/ext4/inode.c | 48 +----------------------------- > 2 files changed, 79 insertions(+), 48 deletions(-) > > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index 69ac042fb74b..2883711e8a33 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -33,6 +33,7 @@ > #include "ext4_jbd2.h" > #include "xattr.h" > #include "acl.h" > +#include "truncate.h" > > static bool ext4_dio_supported(struct inode *inode) > { > @@ -233,12 +234,82 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from) > return iov_iter_count(from); > } > > +static int ext4_handle_inode_extension(struct inode *inode, loff_t offset, > + ssize_t written, size_t count) > +{ > + int ret = 0; > + handle_t *handle; > + bool truncate = false; > + u8 blkbits = inode->i_blkbits; > + ext4_lblk_t written_blk, end_blk; > + > + /* > + * Note that EXT4_I(inode)->i_disksize can get extended up to > + * inode->i_size while the IO was running due to writeback of > + * delalloc blocks. But the code in ext4_iomap_alloc() is careful > + * to use zeroed / unwritten extents if this is possible and thus > + * we won't leave uninitialized blocks in a file even if we didn't > + * succeed in writing as much as we planned. > + */ > + WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize); > + if (offset + count <= EXT4_I(inode)->i_disksize) > + return written < 0 ? written : 0; > + > + if (written < 0) { > + ret = written; > + goto truncate; > + } > + > + handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); > + if (IS_ERR(handle)) { > + ret = PTR_ERR(handle); > + goto truncate; > + } > + > + if (ext4_update_inode_size(inode, offset + written)) > + ext4_mark_inode_dirty(handle, inode); > + > + /* > + * We may need to truncate allocated but not written blocks > + * beyond EOF. > + */ > + written_blk = ALIGN(offset + written, 1 << blkbits); > + end_blk = ALIGN(offset + count, 1 << blkbits); > + if (written_blk < end_blk && ext4_can_truncate(inode)) > + truncate = true; > + > + /* > + * Remove the inode from the orphan list if it has been > + * extended and everything went OK. > + */ > + if (!truncate && inode->i_nlink) > + ext4_orphan_del(handle, inode); > + ext4_journal_stop(handle); > + > + if (truncate) { > +truncate: > + ext4_truncate_failed_write(inode); > + /* > + * If the truncate operation failed early, then the > + * inode may still be on the orphan list. In that > + * case, we need to try remove the inode from the > + * in-memory linked list. > + */ > + if (inode->i_nlink) > + ext4_orphan_del(NULL, inode); > + } > + return ret; > +} > + > #ifdef CONFIG_FS_DAX > static ssize_t > ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) > { > - struct inode *inode = file_inode(iocb->ki_filp); > + int error; > ssize_t ret; > + size_t count; > + loff_t offset; > + struct inode *inode = file_inode(iocb->ki_filp); > > if (!inode_trylock(inode)) { > if (iocb->ki_flags & IOCB_NOWAIT) > @@ -255,7 +326,13 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) > if (ret) > goto out; > > + offset = iocb->ki_pos; > + count = iov_iter_count(from); > ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops); > + > + error = ext4_handle_inode_extension(inode, offset, ret, count); > + if (error) > + ret = error; > out: > inode_unlock(inode); > if (ret > 0) > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 159ffb92f82d..d616062b603e 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3592,53 +3592,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length, > ssize_t written, unsigned flags, struct iomap *iomap) > { > - int ret = 0; > - handle_t *handle; > - int blkbits = inode->i_blkbits; > - bool truncate = false; > - > - if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT)) > - return 0; > - > - handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); > - if (IS_ERR(handle)) { > - ret = PTR_ERR(handle); > - goto orphan_del; > - } > - if (ext4_update_inode_size(inode, offset + written)) > - ext4_mark_inode_dirty(handle, inode); > - /* > - * We may need to truncate allocated but not written blocks beyond EOF. > - */ > - if (iomap->offset + iomap->length > > - ALIGN(inode->i_size, 1 << blkbits)) { > - ext4_lblk_t written_blk, end_blk; > - > - written_blk = (offset + written) >> blkbits; > - end_blk = (offset + length) >> blkbits; > - if (written_blk < end_blk && ext4_can_truncate(inode)) > - truncate = true; > - } > - /* > - * Remove inode from orphan list if we were extending a inode and > - * everything went fine. > - */ > - if (!truncate && inode->i_nlink && > - !list_empty(&EXT4_I(inode)->i_orphan)) > - ext4_orphan_del(handle, inode); > - ext4_journal_stop(handle); > - if (truncate) { > - ext4_truncate_failed_write(inode); > -orphan_del: > - /* > - * If truncate failed early the inode might still be on the > - * orphan list; we need to make sure the inode is removed from > - * the orphan list in that case. > - */ > - if (inode->i_nlink) > - ext4_orphan_del(NULL, inode); > - } > - return ret; > + return 0; > } > > const struct iomap_ops ext4_iomap_ops = { >