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pnfsblock: merge extents

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Replace a stub, so that extents underlying the layouts are properly
added, merged, or ignored as necessary.

Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
[pnfsblock: delete the new node before put it]
Signed-off-by: Mingyang Guo <guomingyang@nrchpc.ac.cn>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Fred Isaman 2011-07-30 20:52:45 -04:00 committed by Trond Myklebust
parent a60d2ebd93
commit 03341d2cc9
2 changed files with 119 additions and 0 deletions
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13
fs/nfs/blocklayout/blocklayout.h
View File

@ -80,6 +80,14 @@ enum extentclass4 {
EXTENT_LISTS = 2,
};
static inline int bl_choose_list(enum exstate4 state)
{
if (state == PNFS_BLOCK_READ_DATA || state == PNFS_BLOCK_NONE_DATA)
return RO_EXTENT;
else
return RW_EXTENT;
}
struct pnfs_block_layout {
struct pnfs_layout_hdr bl_layout;
struct pnfs_inval_markings bl_inval; /* tracks INVAL->RW transition */
@ -137,5 +145,10 @@ int nfs4_blk_process_layoutget(struct pnfs_layout_hdr *lo,
/* blocklayoutdm.c */
void bl_free_block_dev(struct pnfs_block_dev *bdev);
/* extents.c */
void bl_put_extent(struct pnfs_block_extent *be);
struct pnfs_block_extent *bl_alloc_extent(void);
int bl_add_merge_extent(struct pnfs_block_layout *bl,
struct pnfs_block_extent *new);
#endif /* FS_NFS_NFS4BLOCKLAYOUT_H */

106
fs/nfs/blocklayout/extents.c
View File

@ -87,3 +87,109 @@ static void print_elist(struct list_head *list)
}
dprintk("****************\n");
}
static inline int
extents_consistent(struct pnfs_block_extent *old, struct pnfs_block_extent *new)
{
/* Note this assumes new->be_f_offset >= old->be_f_offset */
return (new->be_state == old->be_state) &&
((new->be_state == PNFS_BLOCK_NONE_DATA) ||
((new->be_v_offset - old->be_v_offset ==
new->be_f_offset - old->be_f_offset) &&
new->be_mdev == old->be_mdev));
}
/* Adds new to appropriate list in bl, modifying new and removing existing
* extents as appropriate to deal with overlaps.
*
* See bl_find_get_extent for list constraints.
*
* Refcount on new is already set. If end up not using it, or error out,
* need to put the reference.
*
* bl->bl_ext_lock is held by caller.
*/
int
bl_add_merge_extent(struct pnfs_block_layout *bl,
struct pnfs_block_extent *new)
{
struct pnfs_block_extent *be, *tmp;
sector_t end = new->be_f_offset + new->be_length;
struct list_head *list;
dprintk("%s enter with be=%p\n", __func__, new);
print_bl_extent(new);
list = &bl->bl_extents[bl_choose_list(new->be_state)];
print_elist(list);
/* Scan for proper place to insert, extending new to the left
* as much as possible.
*/
list_for_each_entry_safe(be, tmp, list, be_node) {
if (new->be_f_offset < be->be_f_offset)
break;
if (end <= be->be_f_offset + be->be_length) {
/* new is a subset of existing be*/
if (extents_consistent(be, new)) {
dprintk("%s: new is subset, ignoring\n",
__func__);
bl_put_extent(new);
return 0;
} else
goto out_err;
} else if (new->be_f_offset <=
be->be_f_offset + be->be_length) {
/* new overlaps or abuts existing be */
if (extents_consistent(be, new)) {
/* extend new to fully replace be */
new->be_length += new->be_f_offset -
be->be_f_offset;
new->be_f_offset = be->be_f_offset;
new->be_v_offset = be->be_v_offset;
dprintk("%s: removing %p\n", __func__, be);
list_del(&be->be_node);
bl_put_extent(be);
} else if (new->be_f_offset !=
be->be_f_offset + be->be_length)
goto out_err;
}
}
/* Note that if we never hit the above break, be will not point to a
* valid extent. However, in that case &be->be_node==list.
*/
list_add_tail(&new->be_node, &be->be_node);
dprintk("%s: inserting new\n", __func__);
print_elist(list);
/* Scan forward for overlaps. If we find any, extend new and
* remove the overlapped extent.
*/
be = list_prepare_entry(new, list, be_node);
list_for_each_entry_safe_continue(be, tmp, list, be_node) {
if (end < be->be_f_offset)
break;
/* new overlaps or abuts existing be */
if (extents_consistent(be, new)) {
if (end < be->be_f_offset + be->be_length) {
/* extend new to fully cover be */
end = be->be_f_offset + be->be_length;
new->be_length = end - new->be_f_offset;
}
dprintk("%s: removing %p\n", __func__, be);
list_del(&be->be_node);
bl_put_extent(be);
} else if (end != be->be_f_offset) {
list_del(&new->be_node);
goto out_err;
}
}
dprintk("%s: after merging\n", __func__);
print_elist(list);
/* FIXME - The per-list consistency checks have all been done,
* should now check cross-list consistency.
*/
return 0;
out_err:
bl_put_extent(new);
return -EIO;
}