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gfs2: Fix gfs2_testbit to use clone bitmaps

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Function gfs2_testbit is called in three places. Two of those places,
gfs2_alloc_extent and gfs2_unaligned_extlen, should be using the clone
bitmaps, not the "real" bitmaps. Function gfs2_unaligned_extlen is used
by the block reservations scheme to determine the length of an extent of
free blocks. Before this patch, it wasn't using the clone bitmap, which
means recently-freed blocks were treated as free blocks for the purposes
of an allocation.

This patch adds a new parameter to gfs2_testbit to indicate whether or
not the clone bitmaps should be used (if available).

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Bob Peterson 2018-08-07 10:07:00 -05:00
parent 21e2156f3c
commit dffe12a828
2 changed files with 40 additions and 25 deletions
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21
fs/gfs2/incore.h
View File

@ -65,6 +65,27 @@ struct gfs2_log_operations {
#define GBF_FULL 1
/**
* Clone bitmaps (bi_clone):
*
* - When a block is freed, we remember the previous state of the block in the
* clone bitmap, and only mark the block as free in the real bitmap.
*
* - When looking for a block to allocate, we check for a free block in the
* clone bitmap, and if no clone bitmap exists, in the real bitmap.
*
* - For allocating a block, we mark it as allocated in the real bitmap, and if
* a clone bitmap exists, also in the clone bitmap.
*
* - At the end of a log_flush, we copy the real bitmap into the clone bitmap
* to make the clone bitmap reflect the current allocation state.
* (Alternatively, we could remove the clone bitmap.)
*
* The clone bitmaps are in-core only, and is never written to disk.
*
* These steps ensure that blocks which have been freed in a transaction cannot
* be reallocated in that same transaction.
*/
struct gfs2_bitmap {
struct buffer_head *bi_bh;
char *bi_clone;

44
fs/gfs2/rgrp.c
View File

@ -123,17 +123,26 @@ static inline void gfs2_setbit(const struct gfs2_rbm *rbm, bool do_clone,
/**
* gfs2_testbit - test a bit in the bitmaps
* @rbm: The bit to test
* @use_clone: If true, test the clone bitmap, not the official bitmap.
*
* Some callers like gfs2_unaligned_extlen need to test the clone bitmaps,
* not the "real" bitmaps, to avoid allocating recently freed blocks.
*
* Returns: The two bit block state of the requested bit
*/
static inline u8 gfs2_testbit(const struct gfs2_rbm *rbm)
static inline u8 gfs2_testbit(const struct gfs2_rbm *rbm, bool use_clone)
{
struct gfs2_bitmap *bi = rbm_bi(rbm);
const u8 *buffer = bi->bi_bh->b_data + bi->bi_offset;
const u8 *buffer;
const u8 *byte;
unsigned int bit;
if (use_clone && bi->bi_clone)
buffer = bi->bi_clone;
else
buffer = bi->bi_bh->b_data;
buffer += bi->bi_offset;
byte = buffer + (rbm->offset / GFS2_NBBY);
bit = (rbm->offset % GFS2_NBBY) * GFS2_BIT_SIZE;
@ -322,7 +331,7 @@ static bool gfs2_unaligned_extlen(struct gfs2_rbm *rbm, u32 n_unaligned, u32 *le
u8 res;
for (n = 0; n < n_unaligned; n++) {
res = gfs2_testbit(rbm);
res = gfs2_testbit(rbm, true);
if (res != GFS2_BLKST_FREE)
return true;
(*len)--;
@ -2146,26 +2155,6 @@ void gfs2_inplace_release(struct gfs2_inode *ip)
gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
}
/**
* gfs2_get_block_type - Check a block in a RG is of given type
* @rgd: the resource group holding the block
* @block: the block number
*
* Returns: The block type (GFS2_BLKST_*)
*/
static unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block)
{
struct gfs2_rbm rbm = { .rgd = rgd, };
int ret;
ret = gfs2_rbm_from_block(&rbm, block);
WARN_ON_ONCE(ret != 0);
return gfs2_testbit(&rbm);
}
/**
* gfs2_alloc_extent - allocate an extent from a given bitmap
* @rbm: the resource group information
@ -2190,7 +2179,7 @@ static void gfs2_alloc_extent(const struct gfs2_rbm *rbm, bool dinode,
block++;
while (*n < elen) {
ret = gfs2_rbm_from_block(&pos, block);
if (ret || gfs2_testbit(&pos) != GFS2_BLKST_FREE)
if (ret || gfs2_testbit(&pos, true) != GFS2_BLKST_FREE)
break;
gfs2_trans_add_meta(pos.rgd->rd_gl, rbm_bi(&pos)->bi_bh);
gfs2_setbit(&pos, true, GFS2_BLKST_USED);
@ -2543,6 +2532,7 @@ int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type)
{
struct gfs2_rgrpd *rgd;
struct gfs2_holder rgd_gh;
struct gfs2_rbm rbm;
int error = -EINVAL;
rgd = gfs2_blk2rgrpd(sdp, no_addr, 1);
@ -2553,7 +2543,11 @@ int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type)
if (error)
goto fail;
if (gfs2_get_block_type(rgd, no_addr) != type)
rbm.rgd = rgd;
error = gfs2_rbm_from_block(&rbm, no_addr);
WARN_ON_ONCE(error != 0);
if (gfs2_testbit(&rbm, false) != type)
error = -ESTALE;
gfs2_glock_dq_uninit(&rgd_gh);