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Wong" To: Chandan Babu R Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH V11 05/14] xfs: Check for extent overflow when adding/removing dir entries Message-ID: <20201203190422.GB106271@magnolia> References: <20201117134416.207945-1-chandanrlinux@gmail.com> <20201117134416.207945-6-chandanrlinux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201117134416.207945-6-chandanrlinux@gmail.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9824 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 bulkscore=0 phishscore=0 mlxscore=0 adultscore=0 malwarescore=0 suspectscore=5 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012030110 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9824 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 bulkscore=0 suspectscore=5 phishscore=0 mlxlogscore=999 lowpriorityscore=0 malwarescore=0 priorityscore=1501 spamscore=0 impostorscore=0 clxscore=1015 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012030110 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Nov 17, 2020 at 07:14:07PM +0530, Chandan Babu R wrote: > Directory entry addition/removal can cause the following, > 1. Data block can be added/removed. > A new extent can cause extent count to increase by 1. > 2. Free disk block can be added/removed. > Same behaviour as described above for Data block. > 3. Dabtree blocks. > XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these > can be new extents. Hence extent count can increase by > XFS_DA_NODE_MAXDEPTH. > > To be able to always remove an existing directory entry, when adding a > new directory entry we make sure to reserve inode fork extent count > required for removing a directory entry in addition to that required for > the directory entry add operation. > > Signed-off-by: Chandan Babu R > --- > fs/xfs/libxfs/xfs_inode_fork.h | 13 +++++++++++++ > fs/xfs/xfs_inode.c | 27 +++++++++++++++++++++++++++ > fs/xfs/xfs_symlink.c | 5 +++++ > 3 files changed, 45 insertions(+) > > diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h > index 5de2f07d0dd5..fd93fdc67ee4 100644 > --- a/fs/xfs/libxfs/xfs_inode_fork.h > +++ b/fs/xfs/libxfs/xfs_inode_fork.h > @@ -57,6 +57,19 @@ struct xfs_ifork { > #define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \ > (XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks)) > > +/* > + * Directory entry addition/removal can cause the following, > + * 1. Data block can be added/removed. > + * A new extent can cause extent count to increase by 1. > + * 2. Free disk block can be added/removed. > + * Same behaviour as described above for Data block. > + * 3. Dabtree blocks. > + * XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these can be new > + * extents. Hence extent count can increase by XFS_DA_NODE_MAXDEPTH. > + */ > +#define XFS_IEXT_DIR_MANIP_CNT(mp) \ > + ((XFS_DA_NODE_MAXDEPTH + 1 + 1) * (mp)->m_dir_geo->fsbcount) > + > /* > * Fork handling. > */ > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 2bfbcf28b1bd..f7b0b7fce940 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -1177,6 +1177,11 @@ xfs_create( > if (error) > goto out_trans_cancel; > > + error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp) << 1); Er, why did these double since V10? We're only adding one entry, right? > + if (error) > + goto out_trans_cancel; > + > /* > * A newly created regular or special file just has one directory > * entry pointing to them, but a directory also the "." entry > @@ -1393,6 +1398,11 @@ xfs_link( > xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL); > xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL); > > + error = xfs_iext_count_may_overflow(tdp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp) << 1); Same question here. > + if (error) > + goto error_return; > + > /* > * If we are using project inheritance, we only allow hard link > * creation in our tree when the project IDs are the same; else > @@ -2861,6 +2871,11 @@ xfs_remove( > xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL); > xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL); > > + error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp)); > + if (error) > + goto out_trans_cancel; > + > /* > * If we're removing a directory perform some additional validation. > */ > @@ -3221,6 +3236,18 @@ xfs_rename( > if (wip) > xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL); > > + error = xfs_iext_count_may_overflow(src_dp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp)); > + if (error) > + goto out_trans_cancel; > + > + if (target_ip == NULL) { > + error = xfs_iext_count_may_overflow(target_dp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp) << 1); Why did this change to "<< 1" since V10? I'm sorry, but I've lost my recollection on how the accounting works here. This seems (to me anyway ;)) a good candidate for a comment: For a rename within the same dir where target_name doesn't yet exist, we are removing a name and then adding a name. We therefore check for iext overflow with (DIR_MANIP_CNT * 2), right? And I think that "target name does not exist" is synonymous with target_ip == NULL? For a rename between dirs where the target name doesn't exist, we're removing src_name from src_dp and adding target_name to target_dp. Therefore we have to check for DIR_MANIP_CNT overflow on each of src_dp and target_dp, right? For a rename where target_name /does/ exist, we're only removing the src_name, so we have to check for DIR_MANIP_CNT on src_dp, right? For a RENAME_EXCHANGE we're not removing either name, so we don't need to check for iext overflow of src_dp or target_dp, right? > + if (error) > + goto out_trans_cancel; > + } > + > /* > * If we are using project inheritance, we only allow renames > * into our tree when the project IDs are the same; else the > diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c > index 8e88a7ca387e..08aa808fe290 100644 > --- a/fs/xfs/xfs_symlink.c > +++ b/fs/xfs/xfs_symlink.c > @@ -220,6 +220,11 @@ xfs_symlink( > if (error) > goto out_trans_cancel; > > + error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK, > + XFS_IEXT_DIR_MANIP_CNT(mp) << 1); Same question as xfs_create. --D > + if (error) > + goto out_trans_cancel; > + > /* > * Allocate an inode for the symlink. > */ > -- > 2.28.0 >