diff options
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.c | 24 | ||||
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_buf.h | 19 |
2 files changed, 39 insertions, 4 deletions
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index 5105015..98e0e86 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -387,6 +387,8 @@ _xfs_buf_lookup_pages( if (unlikely(page == NULL)) { if (flags & XBF_READ_AHEAD) { bp->b_page_count = i; + for (i = 0; i < bp->b_page_count; i++) + unlock_page(bp->b_pages[i]); return -ENOMEM; } @@ -416,17 +418,24 @@ _xfs_buf_lookup_pages( ASSERT(!PagePrivate(page)); if (!PageUptodate(page)) { page_count--; - if (blocksize < PAGE_CACHE_SIZE && !PagePrivate(page)) { + if (blocksize >= PAGE_CACHE_SIZE) { + if (flags & XBF_READ) + bp->b_flags |= _XBF_PAGE_LOCKED; + } else if (!PagePrivate(page)) { if (test_page_region(page, offset, nbytes)) page_count++; } } - unlock_page(page); bp->b_pages[i] = page; offset = 0; } + if (!(bp->b_flags & _XBF_PAGE_LOCKED)) { + for (i = 0; i < bp->b_page_count; i++) + unlock_page(bp->b_pages[i]); + } + if (page_count == bp->b_page_count) bp->b_flags |= XBF_DONE; @@ -746,6 +755,7 @@ xfs_buf_associate_memory( bp->b_count_desired = len; bp->b_buffer_length = buflen; bp->b_flags |= XBF_MAPPED; + bp->b_flags &= ~_XBF_PAGE_LOCKED; return 0; } @@ -1093,8 +1103,10 @@ _xfs_buf_ioend( xfs_buf_t *bp, int schedule) { - if (atomic_dec_and_test(&bp->b_io_remaining) == 1) + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) { + bp->b_flags &= ~_XBF_PAGE_LOCKED; xfs_buf_ioend(bp, schedule); + } } STATIC void @@ -1125,6 +1137,9 @@ xfs_buf_bio_end_io( if (--bvec >= bio->bi_io_vec) prefetchw(&bvec->bv_page->flags); + + if (bp->b_flags & _XBF_PAGE_LOCKED) + unlock_page(page); } while (bvec >= bio->bi_io_vec); _xfs_buf_ioend(bp, 1); @@ -1163,7 +1178,8 @@ _xfs_buf_ioapply( * filesystem block size is not smaller than the page size. */ if ((bp->b_buffer_length < PAGE_CACHE_SIZE) && - (bp->b_flags & XBF_READ) && + ((bp->b_flags & (XBF_READ|_XBF_PAGE_LOCKED)) == + (XBF_READ|_XBF_PAGE_LOCKED)) && (blocksize >= PAGE_CACHE_SIZE)) { bio = bio_alloc(GFP_NOIO, 1); diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h index 841d788..f948ec7 100644 --- a/fs/xfs/linux-2.6/xfs_buf.h +++ b/fs/xfs/linux-2.6/xfs_buf.h @@ -66,6 +66,25 @@ typedef enum { _XBF_PAGES = (1 << 18), /* backed by refcounted pages */ _XBF_RUN_QUEUES = (1 << 19),/* run block device task queue */ _XBF_DELWRI_Q = (1 << 21), /* buffer on delwri queue */ + + /* + * Special flag for supporting metadata blocks smaller than a FSB. + * + * In this case we can have multiple xfs_buf_t on a single page and + * need to lock out concurrent xfs_buf_t readers as they only + * serialise access to the buffer. + * + * If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation + * between reads of the page. Hence we can have one thread read the + * page and modify it, but then race with another thread that thinks + * the page is not up-to-date and hence reads it again. + * + * The result is that the first modifcation to the page is lost. + * This sort of AGF/AGI reading race can happen when unlinking inodes + * that require truncation and results in the AGI unlinked list + * modifications being lost. + */ + _XBF_PAGE_LOCKED = (1 << 22), } xfs_buf_flags_t; typedef enum { |
