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staging: lustre: fid: fix up debugfs access to ->lcs_space 

lcs_space can change while the lock is not held
if an RPC in underway.  This can be detected by
seq->ls_update being set.

In this case, reading or writing the value should return
-EBUSY.

Also, the D_INFO CDEBUG() which reports the lcs_space being
updated never fires, as it tests the wrong value -
ldebugfs_fid_write_common() returns 'count' on success.

Finally, this return value should be returned from
ldebugfs_fid_space_seq_write(), rather than always returning 'count',
so that errors can be detected.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
NeilBrown 2018-02-20 13:23:38 +11:00 committed by Greg Kroah-Hartman
parent 8ede253133
commit 8689a5027c
1 changed files with 11 additions and 4 deletions
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15
drivers/staging/lustre/lustre/fid/lproc_fid.c
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@ -106,28 +106,35 @@ ldebugfs_fid_space_seq_write(struct file *file,
rc = ldebugfs_fid_write_common(buffer, count, &range);
spin_lock(&seq->lcs_lock);
if (seq->lcs_update)
/* An RPC call is active to update lcs_space */
rc = -EBUSY;
if (rc > 0)
seq->lcs_space = range;
spin_unlock(&seq->lcs_lock);
if (rc == 0) {
if (rc > 0) {
CDEBUG(D_INFO, "%s: Space: " DRANGE "\n",
seq->lcs_name, PRANGE(&range));
}
return count;
return rc;
}
static int
ldebugfs_fid_space_seq_show(struct seq_file *m, void *unused)
{
struct lu_client_seq *seq = (struct lu_client_seq *)m->private;
int rc = 0;
spin_lock(&seq->lcs_lock);
seq_printf(m, "[%#llx - %#llx]:%x:%s\n", PRANGE(&seq->lcs_space));
if (seq->lcs_update)
rc = -EBUSY;
else
seq_printf(m, "[%#llx - %#llx]:%x:%s\n", PRANGE(&seq->lcs_space));
spin_unlock(&seq->lcs_lock);
return 0;
return rc;
}
static ssize_t