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From:   Ritesh Harjani <riteshh@linux.ibm.com>
To:     jack@suse.cz, tytso@mit.edu, linux-ext4@vger.kernel.org
Cc:     linux-fsdevel@vger.kernel.org, mbobrowski@mbobrowski.org,
        riteshh@linux.ibm.com
Subject: [RFCv3 2/4] ext4: Add ext4_ilock & ext4_iunlock API
Date:   Wed, 20 Nov 2019 10:30:22 +0530
In-Reply-To: <20191120050024.11161-1-riteshh@linux.ibm.com>
References: <20191120050024.11161-1-riteshh@linux.ibm.com>
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Message-Id: <20191120050024.11161-3-riteshh@linux.ibm.com>
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk

This adds ext4_ilock/iunlock types of APIs.
This is the preparation APIs to make shared
locking/unlocking & restarting with exclusive
locking/unlocking easier in next patch.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 fs/ext4/ext4.h    | 33 ++++++++++++++++++++++++++++++
 fs/ext4/extents.c | 16 +++++++--------
 fs/ext4/file.c    | 52 +++++++++++++++++++++++------------------------
 fs/ext4/inode.c   |  4 ++--
 fs/ext4/ioctl.c   | 16 +++++++--------
 fs/ext4/super.c   | 12 +++++------
 fs/ext4/xattr.c   | 17 ++++++++--------
 7 files changed, 92 insertions(+), 58 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 61987c106511..b4169a92e8d0 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2960,6 +2960,39 @@ do {								\
 #define EXT4_FREECLUSTERS_WATERMARK 0
 #endif
 
+#define EXT4_IOLOCK_EXCL	(1 << 0)
+#define EXT4_IOLOCK_SHARED	(1 << 1)
+
+static inline void ext4_ilock(struct inode *inode, unsigned int iolock)
+{
+	if (iolock == EXT4_IOLOCK_EXCL)
+		inode_lock(inode);
+	else
+		inode_lock_shared(inode);
+}
+
+static inline void ext4_iunlock(struct inode *inode, unsigned int iolock)
+{
+	if (iolock == EXT4_IOLOCK_EXCL)
+		inode_unlock(inode);
+	else
+		inode_unlock_shared(inode);
+}
+
+static inline int ext4_ilock_nowait(struct inode *inode, unsigned int iolock)
+{
+	if (iolock == EXT4_IOLOCK_EXCL)
+		return inode_trylock(inode);
+	else
+		return inode_trylock_shared(inode);
+}
+
+static inline void ext4_ilock_demote(struct inode *inode, unsigned int iolock)
+{
+	BUG_ON(iolock != EXT4_IOLOCK_EXCL);
+	downgrade_write(&inode->i_rwsem);
+}
+
 /* Update i_disksize. Requires i_mutex to avoid races with truncate */
 static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
 {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0e8708b77da6..08dd57558533 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4754,7 +4754,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 	else
 		max_blocks -= lblk;
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 
 	/*
 	 * Indirect files do not support unwritten extnets
@@ -4864,7 +4864,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 
 	ext4_journal_stop(handle);
 out_mutex:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	return ret;
 }
 
@@ -4930,7 +4930,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	if (mode & FALLOC_FL_KEEP_SIZE)
 		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 
 	/*
 	 * We only support preallocation for extent-based files only
@@ -4961,7 +4961,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 						EXT4_I(inode)->i_sync_tid);
 	}
 out:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
 	return ret;
 }
@@ -5509,7 +5509,7 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 			return ret;
 	}
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 	/*
 	 * There is no need to overlap collapse range with EOF, in which case
 	 * it is effectively a truncate operation
@@ -5608,7 +5608,7 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 out_mmap:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
 out_mutex:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	return ret;
 }
 
@@ -5659,7 +5659,7 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
 			return ret;
 	}
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 	/* Currently just for extent based files */
 	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 		ret = -EOPNOTSUPP;
@@ -5786,7 +5786,7 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
 out_mmap:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
 out_mutex:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	return ret;
 }
 
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 977ac58dc718..ebe3f051598d 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -55,14 +55,14 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	struct inode *inode = file_inode(iocb->ki_filp);
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!inode_trylock_shared(inode))
+		if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_SHARED))
 			return -EAGAIN;
 	} else {
-		inode_lock_shared(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_SHARED);
 	}
 
 	if (!ext4_dio_supported(inode)) {
-		inode_unlock_shared(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 		/*
 		 * Fallback to buffered I/O if the operation being performed on
 		 * the inode is not supported by direct I/O. The IOCB_DIRECT
@@ -76,7 +76,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 
 	ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL,
 			   is_sync_kiocb(iocb));
-	inode_unlock_shared(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 
 	file_accessed(iocb->ki_filp);
 	return ret;
@@ -89,22 +89,23 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	ssize_t ret;
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!inode_trylock_shared(inode))
+		if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_SHARED))
 			return -EAGAIN;
 	} else {
-		inode_lock_shared(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_SHARED);
 	}
+
 	/*
 	 * Recheck under inode lock - at this point we are sure it cannot
 	 * change anymore
 	 */
 	if (!IS_DAX(inode)) {
-		inode_unlock_shared(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 		/* Fallback to buffered IO in case we cannot support DAX */
 		return generic_file_read_iter(iocb, to);
 	}
 	ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
-	inode_unlock_shared(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 
 	file_accessed(iocb->ki_filp);
 	return ret;
@@ -244,7 +245,7 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
 	if (iocb->ki_flags & IOCB_NOWAIT)
 		return -EOPNOTSUPP;
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 	ret = ext4_write_checks(iocb, from);
 	if (ret <= 0)
 		goto out;
@@ -254,7 +255,7 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
 	current->backing_dev_info = NULL;
 
 out:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	if (likely(ret > 0)) {
 		iocb->ki_pos += ret;
 		ret = generic_write_sync(iocb, ret);
@@ -372,16 +373,17 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	handle_t *handle;
 	struct inode *inode = file_inode(iocb->ki_filp);
 	bool extend = false, overwrite = false, unaligned_aio = false;
+	unsigned int iolock = EXT4_IOLOCK_EXCL;
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!inode_trylock(inode))
+		if (!ext4_ilock_nowait(inode, iolock))
 			return -EAGAIN;
 	} else {
-		inode_lock(inode);
+		ext4_ilock(inode, iolock);
 	}
 
 	if (!ext4_dio_supported(inode)) {
-		inode_unlock(inode);
+		ext4_iunlock(inode, iolock);
 		/*
 		 * Fallback to buffered I/O if the inode does not support
 		 * direct I/O.
@@ -391,7 +393,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 	ret = ext4_write_checks(iocb, from);
 	if (ret <= 0) {
-		inode_unlock(inode);
+		ext4_iunlock(inode, iolock);
 		return ret;
 	}
 
@@ -416,7 +418,8 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (!unaligned_aio && ext4_overwrite_io(inode, offset, count) &&
 	    ext4_should_dioread_nolock(inode)) {
 		overwrite = true;
-		downgrade_write(&inode->i_rwsem);
+		ext4_ilock_demote(inode, iolock);
+		iolock = EXT4_IOLOCK_SHARED;
 	}
 
 	if (offset + count > EXT4_I(inode)->i_disksize) {
@@ -443,10 +446,7 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		ret = ext4_handle_inode_extension(inode, offset, ret, count);
 
 out:
-	if (overwrite)
-		inode_unlock_shared(inode);
-	else
-		inode_unlock(inode);
+	ext4_iunlock(inode, iolock);
 
 	if (ret >= 0 && iov_iter_count(from)) {
 		ssize_t err;
@@ -489,10 +489,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *inode = file_inode(iocb->ki_filp);
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!inode_trylock(inode))
+		if (!ext4_ilock_nowait(inode, EXT4_IOLOCK_EXCL))
 			return -EAGAIN;
 	} else {
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 	}
 
 	ret = ext4_write_checks(iocb, from);
@@ -524,7 +524,7 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (extend)
 		ret = ext4_handle_inode_extension(inode, offset, ret, count);
 out:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	if (ret > 0)
 		ret = generic_write_sync(iocb, ret);
 	return ret;
@@ -757,16 +757,16 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 		return generic_file_llseek_size(file, offset, whence,
 						maxbytes, i_size_read(inode));
 	case SEEK_HOLE:
-		inode_lock_shared(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_SHARED);
 		offset = iomap_seek_hole(inode, offset,
 					 &ext4_iomap_report_ops);
-		inode_unlock_shared(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 		break;
 	case SEEK_DATA:
-		inode_lock_shared(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_SHARED);
 		offset = iomap_seek_data(inode, offset,
 					 &ext4_iomap_report_ops);
-		inode_unlock_shared(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_SHARED);
 		break;
 	}
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 381813205f99..39dcc22667a1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3930,7 +3930,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
 			return ret;
 	}
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 
 	/* No need to punch hole beyond i_size */
 	if (offset >= inode->i_size)
@@ -4037,7 +4037,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
 out_dio:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
 out_mutex:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	return ret;
 }
 
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 0b7f316fd30f..43b7a23dc57b 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -855,13 +855,13 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		if (err)
 			return err;
 
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		err = ext4_ioctl_check_immutable(inode,
 				from_kprojid(&init_user_ns, ei->i_projid),
 				flags);
 		if (!err)
 			err = ext4_ioctl_setflags(inode, flags);
-		inode_unlock(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 		mnt_drop_write_file(filp);
 		return err;
 	}
@@ -892,7 +892,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			goto setversion_out;
 		}
 
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
 		if (IS_ERR(handle)) {
 			err = PTR_ERR(handle);
@@ -907,7 +907,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		ext4_journal_stop(handle);
 
 unlock_out:
-		inode_unlock(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 setversion_out:
 		mnt_drop_write_file(filp);
 		return err;
@@ -1026,9 +1026,9 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		 * ext4_ext_swap_inode_data before we switch the
 		 * inode format to prevent read.
 		 */
-		inode_lock((inode));
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		err = ext4_ext_migrate(inode);
-		inode_unlock((inode));
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 		mnt_drop_write_file(filp);
 		return err;
 	}
@@ -1272,7 +1272,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		if (err)
 			return err;
 
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		ext4_fill_fsxattr(inode, &old_fa);
 		err = vfs_ioc_fssetxattr_check(inode, &old_fa, &fa);
 		if (err)
@@ -1287,7 +1287,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			goto out;
 		err = ext4_ioctl_setproject(filp, fa.fsx_projid);
 out:
-		inode_unlock(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 		mnt_drop_write_file(filp);
 		return err;
 	}
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7796e2ffc294..48b83b2cf0ad 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2682,12 +2682,12 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 					__func__, inode->i_ino, inode->i_size);
 			jbd_debug(2, "truncating inode %lu to %lld bytes\n",
 				  inode->i_ino, inode->i_size);
-			inode_lock(inode);
+			ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 			truncate_inode_pages(inode->i_mapping, inode->i_size);
 			ret = ext4_truncate(inode);
 			if (ret)
 				ext4_std_error(inode->i_sb, ret);
-			inode_unlock(inode);
+			ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 			nr_truncates++;
 		} else {
 			if (test_opt(sb, DEBUG))
@@ -5785,7 +5785,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 		 * files. If this fails, we return success anyway since quotas
 		 * are already enabled and this is not a hard failure.
 		 */
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		handle = ext4_journal_start(inode, EXT4_HT_QUOTA, 1);
 		if (IS_ERR(handle))
 			goto unlock_inode;
@@ -5795,7 +5795,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 		ext4_mark_inode_dirty(handle, inode);
 		ext4_journal_stop(handle);
 	unlock_inode:
-		inode_unlock(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	}
 	return err;
 }
@@ -5887,7 +5887,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
 	if (err || ext4_has_feature_quota(sb))
 		goto out_put;
 
-	inode_lock(inode);
+	ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 	/*
 	 * Update modification times of quota files when userspace can
 	 * start looking at them. If we fail, we return success anyway since
@@ -5902,7 +5902,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
 	ext4_mark_inode_dirty(handle, inode);
 	ext4_journal_stop(handle);
 out_unlock:
-	inode_unlock(inode);
+	ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 out_put:
 	lockdep_set_quota_inode(inode, I_DATA_SEM_NORMAL);
 	iput(inode);
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 8966a5439a22..5c2dcc4c836a 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -422,9 +422,9 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 		ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
 		ext4_xattr_inode_set_ref(inode, 1);
 	} else {
-		inode_lock(inode);
+		ext4_ilock(inode, EXT4_IOLOCK_EXCL);
 		inode->i_flags |= S_NOQUOTA;
-		inode_unlock(inode);
+		ext4_iunlock(inode, EXT4_IOLOCK_EXCL);
 	}
 
 	*ea_inode = inode;
@@ -976,7 +976,7 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
 	u32 hash;
 	int ret;
 
-	inode_lock(ea_inode);
+	ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
 
 	ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
 	if (ret)
@@ -1030,7 +1030,7 @@ static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
 		ext4_warning_inode(ea_inode,
 				   "ext4_mark_iloc_dirty() failed ret=%d", ret);
 out:
-	inode_unlock(ea_inode);
+	ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
 	return ret;
 }
 
@@ -1380,10 +1380,11 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
 		block += 1;
 	}
 
-	inode_lock(ea_inode);
+	ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
 	i_size_write(ea_inode, wsize);
 	ext4_update_i_disksize(ea_inode, wsize);
-	inode_unlock(ea_inode);
+	ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
+
 
 	ext4_mark_inode_dirty(handle, ea_inode);
 
@@ -1432,9 +1433,9 @@ static struct inode *ext4_xattr_inode_create(handle_t *handle,
 		 */
 		dquot_free_inode(ea_inode);
 		dquot_drop(ea_inode);
-		inode_lock(ea_inode);
+		ext4_ilock(ea_inode, EXT4_IOLOCK_EXCL);
 		ea_inode->i_flags |= S_NOQUOTA;
-		inode_unlock(ea_inode);
+		ext4_iunlock(ea_inode, EXT4_IOLOCK_EXCL);
 	}
 
 	return ea_inode;
-- 
2.21.0