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Subject[PATCH] f2fs: fix to avoid race when accessing last_disk_size
Date
last_disk_size could be wrong due to concurrently updating, so using
i_sem semaphore to make last_disk_size updating exclusive to fix this
issue.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/data.c | 3 +++
fs/f2fs/f2fs.h | 10 ++++++++--
fs/f2fs/file.c | 4 ++++
3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 77c238b81e32..467f56521e9b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1569,8 +1569,11 @@ static int __write_data_page(struct page *page, bool *submitted,
err = do_write_data_page(&fio);
}
}
+
+ down_write(&F2FS_I(inode)->i_sem);
if (F2FS_I(inode)->last_disk_size < psize)
F2FS_I(inode)->last_disk_size = psize;
+ up_write(&F2FS_I(inode)->i_sem);

done:
if (err && err != -ENOENT)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 5bd7631975f5..08190df79195 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2313,9 +2313,10 @@ static inline void clear_file(struct inode *inode, int type)

static inline bool f2fs_skip_inode_update(struct inode *inode, int dsync)
{
+ bool ret;
+
if (dsync) {
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
- bool ret;

spin_lock(&sbi->inode_lock[DIRTY_META]);
ret = list_empty(&F2FS_I(inode)->gdirty_list);
@@ -2326,7 +2327,12 @@ static inline bool f2fs_skip_inode_update(struct inode *inode, int dsync)
file_keep_isize(inode) ||
i_size_read(inode) & PAGE_MASK)
return false;
- return F2FS_I(inode)->last_disk_size == i_size_read(inode);
+
+ down_read(&F2FS_I(inode)->i_sem);
+ ret = F2FS_I(inode)->last_disk_size == i_size_read(inode);
+ up_read(&F2FS_I(inode)->i_sem);
+
+ return ret;
}

static inline int f2fs_readonly(struct super_block *sb)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 463f7cd17f71..fe92fb0d7bfe 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -802,6 +802,10 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
inode->i_mtime = inode->i_ctime = current_time(inode);
}

+ down_write(&F2FS_I(inode)->i_sem);
+ F2FS_I(inode)->last_disk_size = i_size_read(inode);
+ up_write(&F2FS_I(inode)->i_sem);
+
size_changed = true;
}

--
2.13.1.388.g69e6b9b4f4a9
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