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gfs2: Clean up after gfs2_create_inode rework

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Since commit 3d36e57ff7 ("gfs2: gfs2_create_inode rework"),
gfs2_evict_inode() and gfs2_create_inode() / gfs2_inode_lookup() will
synchronize via the inode hash table and we can be certain that once a
new inode is inserted into the inode hash table(), gfs2_evict_inode()
has completely destroyed any previous versions.  We no longer need to
worry about overlapping inode object lifespans.  Update the code and
comments accordingly.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2022-12-04 03:48:52 +01:00
parent 97236ad5a6
commit 764665c677
2 changed files with 14 additions and 21 deletions
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14
fs/gfs2/glock.h
View file

@ -322,20 +322,6 @@ static inline void glock_set_object(struct gfs2_glock *gl, void *object)
/**
* glock_clear_object - clear the gl_object field of a glock
* @gl: the glock
* @object: the object
*
* I'd love to similarly add this:
* else if (gfs2_assert_warn(gl->gl_sbd, gl->gl_object == object))
* gfs2_dump_glock(NULL, gl, true);
* Unfortunately, that's not possible because as soon as gfs2_delete_inode
* frees the block in the rgrp, another process can reassign it for an I_NEW
* inode in gfs2_create_inode because that calls new_inode, not gfs2_iget.
* That means gfs2_delete_inode may subsequently try to call this function
* for a glock that's already pointing to a brand new inode. If we clear the
* new inode's gl_object, we'll introduce metadata corruption. Function
* gfs2_delete_inode calls clear_inode which calls gfs2_clear_inode which also
* tries to clear gl_object, so it's more than just gfs2_delete_inode.
*
*/
static inline void glock_clear_object(struct gfs2_glock *gl, void *object)
{

21
fs/gfs2/super.c
View file

@ -1304,14 +1304,21 @@ static int evict_unlinked_inode(struct inode *inode)
goto out;
}
/* We're about to clear the bitmap for the dinode, but as soon as we
do, gfs2_create_inode can create another inode at the same block
location and try to set gl_object again. We clear gl_object here so
that subsequent inode creates don't see an old gl_object. */
if (ip->i_gl) {
glock_clear_object(ip->i_gl, ip);
if (ip->i_gl)
gfs2_inode_remember_delete(ip->i_gl, ip->i_no_formal_ino);
}
/*
* As soon as we clear the bitmap for the dinode, gfs2_create_inode()
* can get called to recreate it, or even gfs2_inode_lookup() if the
* inode was recreated on another node in the meantime.
*
* However, inserting the new inode into the inode hash table will not
* succeed until the old inode is removed, and that only happens after
* ->evict_inode() returns. The new inode is attached to its inode and
* iopen glocks after inserting it into the inode hash table, so at
* that point we can be sure that both glocks are unused.
*/
ret = gfs2_dinode_dealloc(ip);
out:
return ret;