On Thu, May 26, 2022 at 10:43:51PM -0700, Christoph Hellwig wrote: > > static ssize_t jfs_quota_read(struct super_block *sb, int type, char *data, > > + size_t len, loff_t pos) > > And this whole helper is generic now. It might be worth to move it > into fs/quota/dquot.c as generic_quota_read. I've been working on that this week. Unfortunately, you have to convert both quota_read and quota_write at the same time, it turns out. At least ext4_quota_write() uses the bdev's inode's page cache to back the buffer_heads, so quota_read() and quota_write() are incoherent with each other: 00017 gqr: mapping:00000000ee19acfb index:0x1 pos:0x1470 len:0x30 00017 4qw: mapping:000000007f9a811e index:0x18405 pos:0x1440 len:0x30 I don't know if there's a way around this. Can't really use read_mapping_folio() on the bdev's inode in generic_quota_read() -- the blocks for a given page might be fragmented on disk. I don't know if there's a way to tell ext4_bread() to use the inode's page cache instead of the bdev's. And if we did that, would it even work as being part of a transaction?
