diff options
| -rw-r--r-- | fs/reiserfs/stree.c | 42 |
1 files changed, 34 insertions, 8 deletions
diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c index 960c9114f6d..6b025a42d51 100644 --- a/fs/reiserfs/stree.c +++ b/fs/reiserfs/stree.c @@ -519,12 +519,22 @@ static int is_tree_node(struct buffer_head *bh, int level) #define SEARCH_BY_KEY_READA 16 -/* The function is NOT SCHEDULE-SAFE! */ -static void search_by_key_reada(struct super_block *s, +/* + * The function is NOT SCHEDULE-SAFE! + * It might unlock the write lock if we needed to wait for a block + * to be read. Note that in this case it won't recover the lock to avoid + * high contention resulting from too much lock requests, especially + * the caller (search_by_key) will perform other schedule-unsafe + * operations just after calling this function. + * + * @return true if we have unlocked + */ +static bool search_by_key_reada(struct super_block *s, struct buffer_head **bh, b_blocknr_t *b, int num) { int i, j; + bool unlocked = false; for (i = 0; i < num; i++) { bh[i] = sb_getblk(s, b[i]); @@ -536,16 +546,21 @@ static void search_by_key_reada(struct super_block *s, * the lock. But it's still fine because we check later * if the tree changed */ - reiserfs_write_unlock(s); for (j = 0; j < i; j++) { /* * note, this needs attention if we are getting rid of the BKL * you have to make sure the prepared bit isn't set on this buffer */ - if (!buffer_uptodate(bh[j])) + if (!buffer_uptodate(bh[j])) { + if (!unlocked) { + reiserfs_write_unlock(s); + unlocked = true; + } ll_rw_block(READA, 1, bh + j); + } brelse(bh[j]); } + return unlocked; } /************************************************************************** @@ -633,15 +648,26 @@ int search_by_key(struct super_block *sb, const struct cpu_key *key, /* Key to s have a pointer to it. */ if ((bh = last_element->pe_buffer = sb_getblk(sb, block_number))) { + bool unlocked = false; + if (!buffer_uptodate(bh) && reada_count > 1) - /* will unlock the write lock */ - search_by_key_reada(sb, reada_bh, + /* may unlock the write lock */ + unlocked = search_by_key_reada(sb, reada_bh, reada_blocks, reada_count); - else + /* + * If we haven't already unlocked the write lock, + * then we need to do that here before reading + * the current block + */ + if (!buffer_uptodate(bh) && !unlocked) { reiserfs_write_unlock(sb); + unlocked = true; + } ll_rw_block(READ, 1, &bh); wait_on_buffer(bh); - reiserfs_write_lock(sb); + + if (unlocked) + reiserfs_write_lock(sb); if (!buffer_uptodate(bh)) goto io_error; } else { |