diff options
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 7ba58386bee..39ff14403d1 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1181,7 +1181,20 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size) void mark_buffer_dirty(struct buffer_head *bh) { WARN_ON_ONCE(!buffer_uptodate(bh)); - if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) + + /* + * Very *carefully* optimize the it-is-already-dirty case. + * + * Don't let the final "is it dirty" escape to before we + * perhaps modified the buffer. + */ + if (buffer_dirty(bh)) { + smp_mb(); + if (buffer_dirty(bh)) + return; + } + + if (!test_set_buffer_dirty(bh)) __set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0); } @@ -2564,14 +2577,13 @@ int nobh_write_end(struct file *file, struct address_space *mapping, struct inode *inode = page->mapping->host; struct buffer_head *head = fsdata; struct buffer_head *bh; + BUG_ON(fsdata != NULL && page_has_buffers(page)); - if (!PageMappedToDisk(page)) { - if (unlikely(copied < len) && !page_has_buffers(page)) - attach_nobh_buffers(page, head); - if (page_has_buffers(page)) - return generic_write_end(file, mapping, pos, len, - copied, page, fsdata); - } + if (unlikely(copied < len) && !page_has_buffers(page)) + attach_nobh_buffers(page, head); + if (page_has_buffers(page)) + return generic_write_end(file, mapping, pos, len, + copied, page, fsdata); SetPageUptodate(page); set_page_dirty(page); |