linux-ext4 - [PATCH] ext2: delay discarding block reservation

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Message-Id: <20200622012526.4688-1-cgxu519@mykernel.net>
Date:   Mon, 22 Jun 2020 09:25:26 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     jack@...e.com
Cc:     linux-ext4@...r.kernel.org, Chengguang Xu <cgxu519@...ernel.net>
Subject: [PATCH] ext2: delay discarding block reservation

Currently block reservation will be discard when a write mode
file structure is released. It is not efficent for concurrent
writing, so change to discard block reservation when last writer
release file structure.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
 fs/ext2/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 60378ddf1424..28eaf429138b 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -139,7 +139,7 @@ static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
  */
 static int ext2_release_file (struct inode * inode, struct file * filp)
 {
-	if (filp->f_mode & FMODE_WRITE) {
+	if ((filp->f_mode & FMODE_WRITE) && (atomic_read(&inode->i_writecount) == 1)) {
 		mutex_lock(&EXT2_I(inode)->truncate_mutex);
 		ext2_discard_reservation(inode);
 		mutex_unlock(&EXT2_I(inode)->truncate_mutex);
-- 
2.17.2