[5/8] btrfs: Push inode locking and unlocking in buffered/direct write

Commit Message

Goldwyn Rodrigues June 22, 2020, 4:20 p.m. UTC

From: Goldwyn Rodrigues <[e-mail]>

Push inode locking and unlocking closer to where we perform the I/O. For
this we need to move the write checks inside the respective functions as
well.

Signed-off-by: Goldwyn Rodrigues <[e-mail]>
---
 fs/btrfs/file.c | 70 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 24 deletions(-)

Patch

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1a9a0a9e4b3d..aa6be931620b 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1672,7 +1672,7 @@  static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 					       struct iov_iter *i)
 {
 	struct file *file = iocb->ki_filp;
-	loff_t pos = iocb->ki_pos;
+	loff_t pos;
 	struct inode *inode = file_inode(file);
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -1687,14 +1687,29 @@  static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 	bool only_release_metadata = false;
 	bool force_page_uptodate = false;
 	loff_t old_isize = i_size_read(inode);
+	int ilock_flags = 0;
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		ilock_flags |= BTRFS_ILOCK_TRY;
+
+	ret = btrfs_inode_lock(inode, ilock_flags);
+	if (ret < 0)
+		return ret;
+
+	ret = btrfs_write_check(iocb, i);
+	if (ret <= 0)
+		goto out;
+	pos = iocb->ki_pos;
 
 	nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
 			PAGE_SIZE / (sizeof(struct page *)));
 	nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
 	nrptrs = max(nrptrs, 8);
 	pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
-	if (!pages)
-		return -ENOMEM;
+	if (!pages) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	while (iov_iter_count(i) > 0) {
 		struct extent_state *cached_state = NULL;
@@ -1912,6 +1927,8 @@  static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		pagecache_isize_extended(inode, old_isize, iocb->ki_pos);
 		iocb->ki_pos += num_written;
 	}
+out:
+	btrfs_inode_unlock(inode, ilock_flags);
 	return num_written ? num_written : ret;
 }
 
@@ -1942,6 +1959,18 @@  static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	size_t count = 0;
 	bool relock = false;
 	int flags = IOMAP_DIOF_PGINVALID_FAIL;
+	int ilock_flags = 0;
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		ilock_flags |= BTRFS_ILOCK_TRY;
+
+	err = btrfs_inode_lock(inode, ilock_flags);
+	if (err < 0)
+		goto error;
+
+	err = btrfs_write_check(iocb, from);
+	if (err <= 0)
+		goto error;
 
 	if (check_direct_IO(fs_info, from, pos))
 		goto buffered;
@@ -1956,7 +1985,8 @@  static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 		inode_unlock(inode);
 		relock = true;
 	} else if (iocb->ki_flags & IOCB_NOWAIT) {
-		return -EAGAIN;
+		err = -EAGAIN;
+		goto out;
 	}
 
 	if (is_sync_kiocb(iocb))
@@ -1970,10 +2000,13 @@  static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	if (relock)
 		inode_lock(inode);
 
-	if (written < 0 || !iov_iter_count(from))
-		return written;
+	if (written < 0 || !iov_iter_count(from)) {
+		err = written;
+		goto error;
+	}
 
 buffered:
+	btrfs_inode_unlock(inode, ilock_flags);
 	pos = iocb->ki_pos;
 	written_buffered = btrfs_buffered_write(iocb, from);
 	if (written_buffered < 0) {
@@ -1995,8 +2028,13 @@  static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 	iocb->ki_pos = pos + written_buffered;
 	invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
 				 endbyte >> PAGE_SHIFT);
+
 out:
 	return written ? written : err;
+
+error:
+	btrfs_inode_unlock(inode, ilock_flags);
+	return err;
 }
 
 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
@@ -2008,8 +2046,7 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	ssize_t num_written = 0;
 	const bool sync = iocb->ki_flags & IOCB_DSYNC;
-	ssize_t err;
-	int ilock_flags = 0;
+	ssize_t err = 0;
 
 	/*
 	 * If BTRFS flips readonly due to some impossible error
@@ -2024,19 +2061,6 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	    (iocb->ki_flags & IOCB_NOWAIT))
 		return -EOPNOTSUPP;
 
-	if (iocb->ki_flags & IOCB_NOWAIT)
-		ilock_flags |= BTRFS_ILOCK_TRY;
-
-	err = btrfs_inode_lock(inode, ilock_flags);
-	if (err < 0)
-		goto out;
-
-	err = btrfs_write_check(iocb, from);
-	if (err <= 0) {
-		inode_unlock(inode);
-		goto out;
-	}
-
 	if (sync)
 		atomic_inc(&BTRFS_I(inode)->sync_writers);
 
@@ -2046,8 +2070,6 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 		num_written = btrfs_buffered_write(iocb, from);
 	}
 
-	btrfs_inode_unlock(inode, ilock_flags);
-
 	/*
 	 * We also have to set last_sub_trans to the current log transid,
 	 * otherwise subsequent syncs to a file that's been synced in this
@@ -2061,7 +2083,7 @@  static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 
 	if (sync)
 		atomic_dec(&BTRFS_I(inode)->sync_writers);
-out:
+
 	current->backing_dev_info = NULL;
 	return num_written ? num_written : err;
 }