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Message-Id: <6fad2ec25bccbbb9b3effbd18c2d6d6965b9a33c.1681188927.git.ritesh.list@gmail.com> Date: Tue, 11 Apr 2023 10:51:50 +0530 From: "Ritesh Harjani (IBM)" <ritesh.list@...il.com> To: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org Cc: Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>, "Darrick J . Wong" <djwong@...nel.org>, Ojaswin Mujoo <ojaswin@...ux.ibm.com>, "Ritesh Harjani (IBM)" <ritesh.list@...il.com> Subject: [RFCv2 2/8] libfs: Add __generic_file_fsync_nolock implementation Some of the higher layers like iomap takes inode_lock() when calling generic_write_sync(). Also writeback already happens from other paths without inode lock, so it's difficult to say that we really need sync_mapping_buffers() to take any inode locking here. Having said that, let's add a _nolock variant of this function in libfs for now so that filesystems like ext2 and ext4's nojournal mode can use it. Ext4 when got converted to iomap for direct-io already copied it's own variant of __generic_file_fsync() without lock. Hence let's add a helper API and use it both in ext2 and ext4. Later we can review other filesystems as well to see if we can make _nolock as the default path if inode_lock() is not necessary here. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com> --- fs/libfs.c | 43 +++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 1 + 2 files changed, 44 insertions(+) diff --git a/fs/libfs.c b/fs/libfs.c index 4eda519c3002..d2dfb72e3cf8 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1110,6 +1110,49 @@ struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, } EXPORT_SYMBOL_GPL(generic_fh_to_parent); +/** + * __generic_file_fsync_nolock - generic fsync implementation for simple + * filesystems with no inode lock + * + * @file: file to synchronize + * @start: start offset in bytes + * @end: end offset in bytes (inclusive) + * @datasync: only synchronize essential metadata if true + * + * This is a generic implementation of the fsync method for simple + * filesystems which track all non-inode metadata in the buffers list + * hanging off the address_space structure. + */ +int __generic_file_fsync_nolock(struct file *file, loff_t start, loff_t end, + int datasync) +{ + struct inode *inode = file->f_mapping->host; + int err; + int ret; + + err = file_write_and_wait_range(file, start, end); + if (err) + return err; + + ret = sync_mapping_buffers(inode->i_mapping); + if (!(inode->i_state & I_DIRTY_ALL)) + goto out; + if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) + goto out; + + err = sync_inode_metadata(inode, 1); + if (ret == 0) + ret = err; + +out: + /* check and advance again to catch errors after syncing out buffers */ + err = file_check_and_advance_wb_err(file); + if (ret == 0) + ret = err; + return ret; +} +EXPORT_SYMBOL(__generic_file_fsync_nolock); + /** * __generic_file_fsync - generic fsync implementation for simple filesystems * diff --git a/include/linux/fs.h b/include/linux/fs.h index c85916e9f7db..21d2b5670308 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2935,6 +2935,7 @@ extern ssize_t simple_read_from_buffer(void __user *to, size_t count, extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, const void __user *from, size_t count); +extern int __generic_file_fsync_nolock(struct file *, loff_t, loff_t, int); extern int __generic_file_fsync(struct file *, loff_t, loff_t, int); extern int generic_file_fsync(struct file *, loff_t, loff_t, int); -- 2.39.2
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