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gfs2: gfs2_create_inode rework

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When gfs2_lookup_by_inum() calls gfs2_inode_lookup() for an uncached
inode, gfs2_inode_lookup() will place a new tentative inode into the
inode cache before verifying that there is a valid inode at the given
address.  This can race with gfs2_create_inode() which doesn't check for
duplicates inodes.  gfs2_create_inode() will try to assign the new inode
to the corresponding inode glock, and glock_set_object() will complain
that the glock is still in use by gfs2_inode_lookup's tentative inode.

We noticed this bug after adding commit 486408d690 ("gfs2: Cancel
remote delete work asynchronously") which allowed delete_work_func() to
race with gfs2_create_inode(), but the same race exists for
open-by-handle.

Fix that by switching from insert_inode_hash() to
insert_inode_locked4(), which does check for duplicate inodes.  We know
we've just managed to to allocate the new inode, so an inode tentatively
created by gfs2_inode_lookup() will eventually go away and
insert_inode_locked4() will always succeed.

In addition, don't flush the inode glock work anymore (this can now only
make things worse) and clean up glock_{set,clear}_object for the inode
glock somewhat.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2021-11-30 18:26:15 +01:00
parent 5f6e13baeb
commit 3d36e57ff7
1 changed files with 10 additions and 6 deletions
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16
fs/gfs2/inode.c
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@ -707,18 +707,19 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
error = gfs2_glock_get(sdp, ip->i_no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
if (error)
goto fail_free_inode;
flush_delayed_work(&ip->i_gl->gl_work);
error = gfs2_glock_get(sdp, ip->i_no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
if (error)
goto fail_free_inode;
gfs2_cancel_delete_work(io_gl);
error = insert_inode_locked4(inode, ip->i_no_addr, iget_test, &ip->i_no_addr);
BUG_ON(error);
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, ghs + 1);
if (error)
goto fail_gunlock2;
glock_set_object(ip->i_gl, ip);
error = gfs2_trans_begin(sdp, blocks, 0);
if (error)
goto fail_gunlock2;
@ -734,9 +735,9 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
if (error)
goto fail_gunlock2;
glock_set_object(ip->i_gl, ip);
glock_set_object(io_gl, ip);
gfs2_set_iop(inode);
insert_inode_hash(inode);
free_vfs_inode = 0; /* After this point, the inode is no longer
considered free. Any failures need to undo
@ -778,17 +779,17 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
gfs2_glock_dq_uninit(ghs + 1);
gfs2_glock_put(io_gl);
gfs2_qa_put(dip);
unlock_new_inode(inode);
return error;
fail_gunlock3:
glock_clear_object(ip->i_gl, ip);
glock_clear_object(io_gl, ip);
gfs2_glock_dq_uninit(&ip->i_iopen_gh);
fail_gunlock2:
glock_clear_object(io_gl, ip);
gfs2_glock_put(io_gl);
fail_free_inode:
if (ip->i_gl) {
glock_clear_object(ip->i_gl, ip);
if (free_vfs_inode) /* else evict will do the put for us */
gfs2_glock_put(ip->i_gl);
}
@ -806,7 +807,10 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
mark_inode_dirty(inode);
set_bit(free_vfs_inode ? GIF_FREE_VFS_INODE : GIF_ALLOC_FAILED,
&GFS2_I(inode)->i_flags);
iput(inode);
if (inode->i_state & I_NEW)
iget_failed(inode);
else
iput(inode);
}
if (gfs2_holder_initialized(ghs + 1))
gfs2_glock_dq_uninit(ghs + 1);