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Linux: s_op: use .free_inode #16788

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Linux: s_op: use .free_inode #16788

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25 changes: 25 additions & 0 deletions config/kernel-inode-free.m4
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_FREE], [
ZFS_LINUX_TEST_SRC([inode_free], [
#include <linux/fs.h>

static void inode_free(struct inode *ip)
{ return; }

static const struct super_operations
iops __attribute__ ((unused)) = {
.free_inode = inode_free,
};
],[])
])

AC_DEFUN([ZFS_AC_KERNEL_INODE_FREE], [
AC_MSG_CHECKING([whether inode_free() is available])
ZFS_LINUX_TEST_RESULT([inode_free], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_INODE_FREE, 1,
[.inode_free() i_op exists])
],[
AC_MSG_RESULT(no)
])
])

2 changes: 2 additions & 0 deletions config/kernel.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
ZFS_AC_KERNEL_SRC_INSERT_INODE_LOCKED
ZFS_AC_KERNEL_SRC_TRUNCATE_SETSIZE
ZFS_AC_KERNEL_SRC_SECURITY_INODE
ZFS_AC_KERNEL_SRC_INODE_FREE
ZFS_AC_KERNEL_SRC_FST_MOUNT
ZFS_AC_KERNEL_SRC_SB_DYING
ZFS_AC_KERNEL_SRC_SET_NLINK
Expand Down Expand Up @@ -187,6 +188,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
ZFS_AC_KERNEL_INSERT_INODE_LOCKED
ZFS_AC_KERNEL_TRUNCATE_SETSIZE
ZFS_AC_KERNEL_SECURITY_INODE
ZFS_AC_KERNEL_INODE_FREE
ZFS_AC_KERNEL_FST_MOUNT
ZFS_AC_KERNEL_SB_DYING
ZFS_AC_KERNEL_SET_NLINK
Expand Down
1 change: 1 addition & 0 deletions include/os/linux/zfs/sys/zfs_znode_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,7 @@ struct znode;
extern int zfs_sync(struct super_block *, int, cred_t *);
extern int zfs_inode_alloc(struct super_block *, struct inode **ip);
extern void zfs_inode_destroy(struct inode *);
extern void zfs_inode_free(struct inode *);
extern void zfs_mark_inode_dirty(struct inode *);
extern boolean_t zfs_relatime_need_update(const struct inode *);
extern zil_replay_func_t *const zfs_replay_vector[TX_MAX_TYPE];
Expand Down
15 changes: 11 additions & 4 deletions module/os/linux/zfs/zfs_znode_os.c
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Original file line number Diff line number Diff line change
Expand Up @@ -371,9 +371,14 @@ zfs_inode_alloc(struct super_block *sb, struct inode **ip)
return (0);
}

/*
* Called in multiple places when an inode should be destroyed.
*/
void
zfs_inode_free(struct inode *ip)
{
znode_t *zp = ITOZ(ip);

kmem_cache_free(znode_cache, zp);
}

void
zfs_inode_destroy(struct inode *ip)
{
Expand All @@ -396,7 +401,9 @@ zfs_inode_destroy(struct inode *ip)
zp->z_xattr_cached = NULL;
}

kmem_cache_free(znode_cache, zp);
#ifndef HAVE_INODE_FREE
zfs_inode_free(ip);
#endif
}

static void
Expand Down
15 changes: 15 additions & 0 deletions module/os/linux/zfs/zpl_super.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,12 +45,20 @@ zpl_inode_alloc(struct super_block *sb)
return (ip);
}

#ifdef HAVE_INODE_FREE
static void
zpl_inode_free(struct inode *ip)
{
zfs_inode_free(ip);
}
#else
static void
zpl_inode_destroy(struct inode *ip)
{
ASSERT(atomic_read(&ip->i_count) == 0);
zfs_inode_destroy(ip);
}
#endif

/*
* Called from __mark_inode_dirty() to reflect that something in the
Expand Down Expand Up @@ -91,6 +99,9 @@ zpl_evict_inode(struct inode *ip)
truncate_setsize(ip, 0);
clear_inode(ip);
zfs_inactive(ip);
#ifdef HAVE_INODE_FREE
zfs_inode_destroy(ip);
#endif
spl_fstrans_unmark(cookie);
}

Expand Down Expand Up @@ -455,7 +466,11 @@ zpl_prune_sb(uint64_t nr_to_scan, void *arg)

const struct super_operations zpl_super_operations = {
.alloc_inode = zpl_inode_alloc,
#ifdef HAVE_INODE_FREE
.free_inode = zpl_inode_free,
#else
.destroy_inode = zpl_inode_destroy,
#endif
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I believe we still want to register .destroy_inode even when .free_inode is available. It's just that the RCU-delayed parts have been moved in to .free_inode.

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Well I tried to adhere to the note in porting.rst to the fullest extent possible, as it doesn't even say that .free_inode is now required if one doesn't want to run into unexplainable behavior (perhaps only with some kernel releases along the way to full folio conversion); I was wondering what more in terms of problems can we expect if I try to go against that note, in a sense of leaving .destroy_inode as it was.

Do you see any consequences of merging destroy_inode into evict_inode from the ZFS point of view? I couldn't think of anything so that's why I decided to do away with destroy_inode by merging it, just an abundance of caution, aka "what else aren't they telling me in the note, when they didn't even say it's mandatory but just recommended"

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I mean, if the inode gets as far as evict_inode being called on it, it's already done and zfs_zget is going to keep looping until it disappears completely, isn't it so?

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@behlendorf ping, what do you think, do we keep it as I propose? I'd like to push this forward but this seems like it needs further input from you :) Thanks!

.dirty_inode = zpl_dirty_inode,
.write_inode = NULL,
.evict_inode = zpl_evict_inode,
Expand Down
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