From cf2404a976268f2b1b3448724c43060acb224034 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 11 Jul 2022 15:22:50 +0100 Subject: [PATCH] btrfs: add optimized btrfs_ino() version for 64 bits systems Currently btrfs_ino() tries to use first the objectid of the inode's location key. This is to avoid truncation of the inode number on 32 bits platforms because the i_ino field of struct inode has the unsigned long type, while the objectid is a 64 bits unsigned type (u64) on every system. This logic was added in commit 33345d01522f81 ("Btrfs: Always use 64bit inode number"). However if we are running on a 64 bits system, we can always directly return the i_ino value from struct inode, which eliminates the need for he special if statement that tests for a location key type of BTRFS_ROOT_ITEM_KEY - in which case i_ino may not have the same value as the objectid in the inode's location objectid, it may have a value of BTRFS_EMPTY_SUBVOL_DIR_OBJECTID, for the case of snapshots of trees with subvolumes/snapshots inside them. So add a special version for 64 bits system that directly returns i_ino of struct inode. This eliminates one branch and reduces the overall code size, since btrfs_ino() is an inline function that is extensively used. Before: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1617487 189240 29032 1835759 1c02ef fs/btrfs/btrfs.ko After: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1612028 189180 29032 1830240 1bed60 fs/btrfs/btrfs.ko Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/btrfs_inode.h | 15 +++++++++++++++ fs/btrfs/tests/btrfs-tests.c | 1 + 2 files changed, 16 insertions(+) diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index a18f90ff16f12..b160b8e124e01 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -279,6 +279,12 @@ static inline void btrfs_insert_inode_hash(struct inode *inode) __insert_inode_hash(inode, h); } +#if BITS_PER_LONG == 32 + +/* + * On 32 bit systems the i_ino of struct inode is 32 bits (unsigned long), so + * we use the inode's location objectid which is a u64 to avoid truncation. + */ static inline u64 btrfs_ino(const struct btrfs_inode *inode) { u64 ino = inode->location.objectid; @@ -289,6 +295,15 @@ static inline u64 btrfs_ino(const struct btrfs_inode *inode) return ino; } +#else + +static inline u64 btrfs_ino(const struct btrfs_inode *inode) +{ + return inode->vfs_inode.i_ino; +} + +#endif + static inline void btrfs_i_size_write(struct btrfs_inode *inode, u64 size) { i_size_write(&inode->vfs_inode, size); diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c index d8e56edd69910..cc9377cf56a33 100644 --- a/fs/btrfs/tests/btrfs-tests.c +++ b/fs/btrfs/tests/btrfs-tests.c @@ -59,6 +59,7 @@ struct inode *btrfs_new_test_inode(void) return NULL; inode->i_mode = S_IFREG; + inode->i_ino = BTRFS_FIRST_FREE_OBJECTID; BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY; BTRFS_I(inode)->location.objectid = BTRFS_FIRST_FREE_OBJECTID; BTRFS_I(inode)->location.offset = 0; -- 2.30.2