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branches/zip: buf_page_init_for_read(): X-latch the block before

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invoking buf_buddy_alloc().  An IO-fixed block must also be x-latched
when block->mutex and buf_pool->mutex are released.

buf_page_create(): Protect the block during buf_buddy_alloc() by
IO-fixing and X-latching it.
This commit is contained in:
marko
2007-01-16 13:45:52 +00:00
parent 631a11391e
commit b68c70121e
1 changed files with 19 additions and 9 deletions
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28
buf/buf0buf.c
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@@ -2245,6 +2245,15 @@ err_exit:
buf_pool->n_pend_reads++;
/* We set a pass-type x-lock on the frame because then the same
thread which called for the read operation (and is running now at
this point of code) can wait for the read to complete by waiting
for the x-lock on the frame; if the x-lock were recursive, the
same thread would illegally get the x-lock before the page read
is completed. The x-lock is cleared by the io-handler thread. */
rw_lock_x_lock_gen(&(block->lock), BUF_IO_READ);
if (zip_size) {
void* data;
page_zip_set_size(&block->page.zip, zip_size);
@@ -2260,15 +2269,6 @@ err_exit:
block->page.zip.data = data;
}
/* We set a pass-type x-lock on the frame because then the same
thread which called for the read operation (and is running now at
this point of code) can wait for the read to complete by waiting
for the x-lock on the frame; if the x-lock were recursive, the
same thread would illegally get the x-lock before the page read
is completed. The x-lock is cleared by the io-handler thread. */
rw_lock_x_lock_gen(&(block->lock), BUF_IO_READ);
mutex_exit(&block->mutex);
mutex_exit(&(buf_pool->mutex));
@@ -2346,6 +2346,13 @@ buf_page_create(
buf_block_buf_fix_inc(block, __FILE__, __LINE__);
buf_pool->n_pages_created++;
/* Prevent race conditions during buf_buddy_alloc(),
which may release and reacquire buf_pool->mutex,
by IO-fixing and X-latching the block. */
buf_page_set_io_fix(&block->page, BUF_IO_READ);
rw_lock_x_lock(&block->lock);
if (zip_size) {
void* data;
page_zip_set_size(&block->page.zip, zip_size);
@@ -2361,6 +2368,9 @@ buf_page_create(
block->page.zip.data = data;
}
buf_page_set_io_fix(&block->page, BUF_IO_NONE);
rw_lock_x_unlock(&block->lock);
mutex_exit(&(buf_pool->mutex));
mtr_memo_push(mtr, block, MTR_MEMO_BUF_FIX);