diff options
| -rw-r--r-- | ext2fs/pager.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/ext2fs/pager.c b/ext2fs/pager.c index a17786f0..9eec69a1 100644 --- a/ext2fs/pager.c +++ b/ext2fs/pager.c @@ -326,15 +326,19 @@ disk_pager_write_page (vm_offset_t page, vm_address_t buf) while (length > 0 && !err) { - int modified; block_t block = boffs_block (offs); - spin_lock (&modified_global_blocks_lock); - modified = clear_bit (block, modified_global_blocks); - spin_unlock (&modified_global_blocks_lock); - - if (modified) - /* This block's been modified, so write it out. */ + /* We don't clear the block modified bit here because this paging + write request may not be the same one that actually set the bit, + and our copy of the page may be out of date; we have to leave + the bit on in case a paging write request corresponding to the + modification comes along later. The bit is only actually ever + cleared if the block is allocated to a file, so this results in + excess writes of blocks from modified pages. Unfortunately I + know of no way to get arount this given the current external + paging interface. XXXX */ + if (test_bit (block, modified_global_blocks)) + /* This block may have been modified, so write it out. */ err = pending_blocks_add (&pb, block); else /* Otherwise just skip it. */ |