GFS2: Clean up quota slot allocation

Quota slot allocation has historically used a vector of pages
and a set of homegrown find/test/set/clear bit functions. Since
the size of the bitmap is likely to be based on the default
qc file size, thats a couple of pages at most. So we ought
to be able to allocate that as a single chunk, with a vmalloc
fallback, just in case of memory fragmentation.

We are then able to use the kernel's own find/test/set/clear
bit functions, rather than rolling our own.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 59d99ec..4b9aa5b 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -733,8 +733,7 @@ struct gfs2_sbd {
        spinlock_t sd_trunc_lock;
 
        unsigned int sd_quota_slots;
-       unsigned int sd_quota_chunks;
-       unsigned char **sd_quota_bitmap;
+       unsigned long *sd_quota_bitmap;
 
        u64 sd_quota_sync_gen;
 

diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 3287d98..79be67a 100644 (file)
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -315,50 +315,30 @@ static void qd_put(struct gfs2_quota_data *qd)
 
 static int slot_get(struct gfs2_quota_data *qd)
 {
-       struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
-       unsigned int c, o = 0, b;
-       unsigned char byte = 0;
+       struct gfs2_sbd *sdp = qd->qd_sbd;
+       unsigned int bit;
+       int error = 0;
 
        spin_lock(&qd_lock);
+       if (qd->qd_slot_count != 0)
+               goto out;
 
-       if (qd->qd_slot_count++) {
-               spin_unlock(&qd_lock);
-               return 0;
+       error = -ENOSPC;
+       bit = find_first_zero_bit(sdp->sd_quota_bitmap, sdp->sd_quota_slots);
+       if (bit < sdp->sd_quota_slots) {
+               set_bit(bit, sdp->sd_quota_bitmap);
+               qd->qd_slot = bit;
+out:
+               qd->qd_slot_count++;
        }
-
-       for (c = 0; c < sdp->sd_quota_chunks; c++)
-               for (o = 0; o < PAGE_SIZE; o++) {
-                       byte = sdp->sd_quota_bitmap[c][o];
-                       if (byte != 0xFF)
-                               goto found;
-               }
-
-       goto fail;
-
-found:
-       for (b = 0; b < 8; b++)
-               if (!(byte & (1 << b)))
-                       break;
-       qd->qd_slot = c * (8 * PAGE_SIZE) + o * 8 + b;
-
-       if (qd->qd_slot >= sdp->sd_quota_slots)
-               goto fail;
-
-       sdp->sd_quota_bitmap[c][o] |= 1 << b;
-
        spin_unlock(&qd_lock);
 
-       return 0;
-
-fail:
-       qd->qd_slot_count--;
-       spin_unlock(&qd_lock);
-       return -ENOSPC;
+       return error;
 }
 
 static void slot_hold(struct gfs2_quota_data *qd)
 {
-       struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
+       struct gfs2_sbd *sdp = qd->qd_sbd;
 
        spin_lock(&qd_lock);
        gfs2_assert(sdp, qd->qd_slot_count);
@@ -366,34 +346,14 @@ static void slot_hold(struct gfs2_quota_data *qd)
        spin_unlock(&qd_lock);
 }
 
-static void gfs2_icbit_munge(struct gfs2_sbd *sdp, unsigned char **bitmap,
-                            unsigned int bit, int new_value)
-{
-       unsigned int c, o, b = bit;
-       int old_value;
-
-       c = b / (8 * PAGE_SIZE);
-       b %= 8 * PAGE_SIZE;
-       o = b / 8;
-       b %= 8;
-
-       old_value = (bitmap[c][o] & (1 << b));
-       gfs2_assert_withdraw(sdp, !old_value != !new_value);
-
-       if (new_value)
-               bitmap[c][o] |= 1 << b;
-       else
-               bitmap[c][o] &= ~(1 << b);
-}
-
 static void slot_put(struct gfs2_quota_data *qd)
 {
-       struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
+       struct gfs2_sbd *sdp = qd->qd_sbd;
 
        spin_lock(&qd_lock);
        gfs2_assert(sdp, qd->qd_slot_count);
        if (!--qd->qd_slot_count) {
-               gfs2_icbit_munge(sdp, sdp->sd_quota_bitmap, qd->qd_slot, 0);
+               BUG_ON(!test_and_clear_bit(qd->qd_slot, sdp->sd_quota_bitmap));
                qd->qd_slot = -1;
        }
        spin_unlock(&qd_lock);
@@ -1269,6 +1229,7 @@ int gfs2_quota_init(struct gfs2_sbd *sdp)
        unsigned int x, slot = 0;
        unsigned int found = 0;
        unsigned int hash;
+       unsigned int bm_size;
        u64 dblock;
        u32 extlen = 0;
        int error;
@@ -1277,20 +1238,16 @@ int gfs2_quota_init(struct gfs2_sbd *sdp)
                return -EIO;
 
        sdp->sd_quota_slots = blocks * sdp->sd_qc_per_block;
-       sdp->sd_quota_chunks = DIV_ROUND_UP(sdp->sd_quota_slots, 8 * PAGE_SIZE);
-
+       bm_size = DIV_ROUND_UP(sdp->sd_quota_slots, 8 * sizeof(unsigned long));
+       bm_size *= sizeof(unsigned long);
        error = -ENOMEM;
-
-       sdp->sd_quota_bitmap = kcalloc(sdp->sd_quota_chunks,
-                                      sizeof(unsigned char *), GFP_NOFS);
+       sdp->sd_quota_bitmap = kmalloc(bm_size, GFP_NOFS|__GFP_NOWARN);
+       if (sdp->sd_quota_bitmap == NULL)
+               sdp->sd_quota_bitmap = __vmalloc(bm_size, GFP_NOFS, PAGE_KERNEL);
        if (!sdp->sd_quota_bitmap)
                return error;
 
-       for (x = 0; x < sdp->sd_quota_chunks; x++) {
-               sdp->sd_quota_bitmap[x] = kzalloc(PAGE_SIZE, GFP_NOFS);
-               if (!sdp->sd_quota_bitmap[x])
-                       goto fail;
-       }
+       memset(sdp->sd_quota_bitmap, 0, bm_size);
 
        for (x = 0; x < blocks; x++) {
                struct buffer_head *bh;
@@ -1339,7 +1296,7 @@ int gfs2_quota_init(struct gfs2_sbd *sdp)
                        qd->qd_slot_count = 1;
 
                        spin_lock(&qd_lock);
-                       gfs2_icbit_munge(sdp, sdp->sd_quota_bitmap, slot, 1);
+                       BUG_ON(test_and_set_bit(slot, sdp->sd_quota_bitmap));
                        list_add(&qd->qd_list, &sdp->sd_quota_list);
                        atomic_inc(&sdp->sd_quota_count);
                        spin_unlock(&qd_lock);
@@ -1370,7 +1327,6 @@ void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
 {
        struct list_head *head = &sdp->sd_quota_list;
        struct gfs2_quota_data *qd;
-       unsigned int x;
 
        spin_lock(&qd_lock);
        while (!list_empty(head)) {
@@ -1401,9 +1357,11 @@ void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
        gfs2_assert_warn(sdp, !atomic_read(&sdp->sd_quota_count));
 
        if (sdp->sd_quota_bitmap) {
-               for (x = 0; x < sdp->sd_quota_chunks; x++)
-                       kfree(sdp->sd_quota_bitmap[x]);
-               kfree(sdp->sd_quota_bitmap);
+               if (is_vmalloc_addr(sdp->sd_quota_bitmap))
+                       vfree(sdp->sd_quota_bitmap);
+               else
+                       kfree(sdp->sd_quota_bitmap);
+               sdp->sd_quota_bitmap = NULL;
        }
 }