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gfs2: Upgrade shared glocks for atime updates

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Commit 20f829999c ("gfs2: Rework read and page fault locking") lifted
the glock lock taking from the low-level ->readpage and ->readahead
address space operations to the higher-level ->read_iter file and
->fault vm operations.  The glocks are still taken in LM_ST_SHARED mode
only.  On filesystems mounted without the noatime option, ->read_iter
sometimes needs to update the atime as well, though.  Right now, this
leads to a failed locking mode assertion in gfs2_dirty_inode.

Fix that by introducing a new update_time inode operation.  There, if
the glock is held non-exclusively, upgrade it to an exclusive lock.

Reported-by: Alexander Aring <aahringo@redhat.com>
Fixes: 20f829999c ("gfs2: Rework read and page fault locking")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2020-11-25 23:37:18 +01:00
parent f39e7d3aae
commit 82e938bd53
1 changed files with 21 additions and 0 deletions
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21
fs/gfs2/inode.c
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@ -2116,6 +2116,25 @@ loff_t gfs2_seek_hole(struct file *file, loff_t offset)
return vfs_setpos(file, ret, inode->i_sb->s_maxbytes);
}
static int gfs2_update_time(struct inode *inode, struct timespec64 *time,
int flags)
{
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_glock *gl = ip->i_gl;
struct gfs2_holder *gh;
int error;
gh = gfs2_glock_is_locked_by_me(gl);
if (gh && !gfs2_glock_is_held_excl(gl)) {
gfs2_glock_dq(gh);
gfs2_holder_reinit(LM_ST_EXCLUSIVE, 0, gh);
error = gfs2_glock_nq(gh);
if (error)
return error;
}
return generic_update_time(inode, time, flags);
}
const struct inode_operations gfs2_file_iops = {
.permission = gfs2_permission,
.setattr = gfs2_setattr,
@ -2124,6 +2143,7 @@ const struct inode_operations gfs2_file_iops = {
.fiemap = gfs2_fiemap,
.get_acl = gfs2_get_acl,
.set_acl = gfs2_set_acl,
.update_time = gfs2_update_time,
};
const struct inode_operations gfs2_dir_iops = {
@ -2143,6 +2163,7 @@ const struct inode_operations gfs2_dir_iops = {
.fiemap = gfs2_fiemap,
.get_acl = gfs2_get_acl,
.set_acl = gfs2_set_acl,
.update_time = gfs2_update_time,
.atomic_open = gfs2_atomic_open,
};