[RFC PATCH v4 30/34] ext4: partial enable iomap for regular file's buffered IO path

Zhang Yi
2024-04-10T15:11:52Z

Partial enable iomap for regular file's buffered IO path on default
mount option, support default filesystem features and bigalloc feature,
doesn't support inline data, fs_verity, fs_crypt, defrag and
data=journal mode yet (these would be supported gradually in the
future). ext4 will fallback to buffered_head path automatically if these
options or features are enable.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/ext4/ext4.h | 1 +
fs/ext4/ialloc.c | 3 +++
fs/ext4/inode.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 36 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2ec6c7884e9a..4e7667b21c2f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2972,6 +2972,7 @@ int ext4_walk_page_buffers(handle_t *handle,
struct buffer_head *bh));
int do_journal_get_write_access(handle_t *handle, struct inode *inode,
struct buffer_head *bh);
+bool ext4_should_use_buffered_iomap(struct inode *inode);
int ext4_nonda_switch(struct super_block *sb);
#define FALL_BACK_TO_NONDELALLOC 1
#define CONVERT_INLINE_DATA 2
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index e9bbb1da2d0a..956b9d69c559 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1336,6 +1336,9 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
}
}

+ if (ext4_should_use_buffered_iomap(inode))
+ ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+
if (ext4_handle_valid(handle)) {
ei->i_sync_tid = handle->h_transaction->t_tid;
ei->i_datasync_tid = handle->h_transaction->t_tid;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5af3b8acf1b9..624eac0cc705 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -770,6 +770,8 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,

if (ext4_has_inline_data(inode))
return -ERANGE;
+ if (WARN_ON(ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)))
+ return -EINVAL;

map.m_lblk = iblock;
map.m_len = bh->b_size >> inode->i_blkbits;
@@ -2567,6 +2569,9 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)

trace_ext4_writepages(inode, wbc);

+ if (WARN_ON(ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)))
+ return -EINVAL;
+
/*
* No pages to write? This is mainly a kludge to avoid starting
* a transaction for special inodes like journal inode on last iput()
@@ -5107,6 +5112,30 @@ static const char *check_igot_inode(struct inode *inode, ext4_iget_flags flags)
return NULL;
}

+bool ext4_should_use_buffered_iomap(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+
+ if (ext4_has_feature_inline_data(sb))
+ return false;
+ if (ext4_has_feature_verity(sb))
+ return false;
+ if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
+ return false;
+ if (!S_ISREG(inode->i_mode))
+ return false;
+ if (IS_DAX(inode))
+ return false;
+ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+ return false;
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
+ return false;
+ if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
+ return false;
+
+ return true;
+}
+
struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
ext4_iget_flags flags, const char *function,
unsigned int line)
@@ -5371,6 +5400,9 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
if (ret)
goto bad_inode;

+ if (ext4_should_use_buffered_iomap(inode))
+ ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+
if (S_ISREG(inode->i_mode)) {
inode->i_op = &ext4_file_inode_operations;
inode->i_fop = &ext4_file_operations;
--
2.39.2