pnfs/blocklayout: update last_write_offset atomically with extents

Block/SCSI layout write completion may add committable extents to the
extent tree before updating the layout's last-written byte under the inode
lock.  If a sync happens before this value is updated, then
prepare_layoutcommit may find and encode these extents which would produce
a LAYOUTCOMMIT request whose encoded extents are larger than the request's
loca_length.

Fix this by using a last-written byte value that is updated atomically with
the extent tree so that commitable extents always match.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Benjamin Coddington 2016-08-22 14:11:16 -04:00 committed by Trond Myklebust
parent b88fa69eaa
commit 41963c10c4
3 changed files with 10 additions and 5 deletions

View File

@ -346,7 +346,7 @@ static void bl_write_cleanup(struct work_struct *work)
PAGE_SIZE - 1) & (loff_t)PAGE_MASK;
ext_tree_mark_written(bl, start >> SECTOR_SHIFT,
(end - start) >> SECTOR_SHIFT);
(end - start) >> SECTOR_SHIFT, end);
}
pnfs_ld_write_done(hdr);

View File

@ -141,6 +141,7 @@ struct pnfs_block_layout {
struct rb_root bl_ext_ro;
spinlock_t bl_ext_lock; /* Protects list manipulation */
bool bl_scsi_layout;
u64 bl_lwb;
};
static inline struct pnfs_block_layout *
@ -182,7 +183,7 @@ int ext_tree_insert(struct pnfs_block_layout *bl,
int ext_tree_remove(struct pnfs_block_layout *bl, bool rw, sector_t start,
sector_t end);
int ext_tree_mark_written(struct pnfs_block_layout *bl, sector_t start,
sector_t len);
sector_t len, u64 lwb);
bool ext_tree_lookup(struct pnfs_block_layout *bl, sector_t isect,
struct pnfs_block_extent *ret, bool rw);
int ext_tree_prepare_commit(struct nfs4_layoutcommit_args *arg);

View File

@ -402,7 +402,7 @@ ext_tree_split(struct rb_root *root, struct pnfs_block_extent *be,
int
ext_tree_mark_written(struct pnfs_block_layout *bl, sector_t start,
sector_t len)
sector_t len, u64 lwb)
{
struct rb_root *root = &bl->bl_ext_rw;
sector_t end = start + len;
@ -471,6 +471,8 @@ ext_tree_mark_written(struct pnfs_block_layout *bl, sector_t start,
}
}
out:
if (bl->bl_lwb < lwb)
bl->bl_lwb = lwb;
spin_unlock(&bl->bl_ext_lock);
__ext_put_deviceids(&tmp);
@ -518,7 +520,7 @@ static __be32 *encode_scsi_range(struct pnfs_block_extent *be, __be32 *p)
}
static int ext_tree_encode_commit(struct pnfs_block_layout *bl, __be32 *p,
size_t buffer_size, size_t *count)
size_t buffer_size, size_t *count, __u64 *lastbyte)
{
struct pnfs_block_extent *be;
int ret = 0;
@ -542,6 +544,8 @@ static int ext_tree_encode_commit(struct pnfs_block_layout *bl, __be32 *p,
p = encode_block_extent(be, p);
be->be_tag = EXTENT_COMMITTING;
}
*lastbyte = bl->bl_lwb - 1;
bl->bl_lwb = 0;
spin_unlock(&bl->bl_ext_lock);
return ret;
@ -564,7 +568,7 @@ ext_tree_prepare_commit(struct nfs4_layoutcommit_args *arg)
arg->layoutupdate_pages = &arg->layoutupdate_page;
retry:
ret = ext_tree_encode_commit(bl, start_p + 1, buffer_size, &count);
ret = ext_tree_encode_commit(bl, start_p + 1, buffer_size, &count, &arg->lastbytewritten);
if (unlikely(ret)) {
ext_tree_free_commitdata(arg, buffer_size);