From b547a88ea5776a8092f7f122ddc20d6720528782 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Thu, 18 Jun 2020 14:54:56 +0200 Subject: btrfs: start deprecation of mount option inode_cache Estimated time of removal of the functionality is 5.11, the option will be still parsed but will have no effect. Reasons for deprecation and removal: - very poor naming choice of the mount option, it's supposed to cache and reuse the inode _numbers_, but it sounds a some generic cache for inodes - the only known usecase where this option would make sense is on a 32bit architecture where inode numbers in one subvolume would be exhausted due to 32bit inode::i_ino - the cache is stored on disk, consumes space, needs to be loaded and written back - new inode number allocation is slower due to lookups into the cache (compared to a simple increment which is the default) - uses the free-space-cache code that is going to be deprecated as well in the future Known problems: - since 2011, returning EEXIST when there's not enough space in a page to store all checksums, see commit 4b9465cb9e38 ("Btrfs: add mount -o inode_cache") Remaining issues: - if the option was enabled, new inodes created, the option disabled again, the cache is still stored on the devices and there's currently no way to remove it Signed-off-by: David Sterba --- fs/btrfs/super.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/btrfs/super.c') diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 76ab6d5d01a9..dac04e28643e 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -821,6 +821,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, } break; case Opt_inode_cache: + btrfs_warn(info, + "the 'inode_cache' option is deprecated and will have no effect from 5.11"); btrfs_set_pending_and_info(info, INODE_MAP_CACHE, "enabling inode map caching"); break; -- cgit v1.2.3