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/openbmc/linux/fs/btrfs/tests/
H A Dbtrfs-tests.cdiff cf2404a976268f2b1b3448724c43060acb224034 Mon Jul 11 09:22:50 CDT 2022 Filipe Manana <fdmanana@suse.com> 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 <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
/openbmc/linux/fs/btrfs/
H A Dbtrfs_inode.hdiff cf2404a976268f2b1b3448724c43060acb224034 Mon Jul 11 09:22:50 CDT 2022 Filipe Manana <fdmanana@suse.com> 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 <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>