From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tao Ma Date: Fri, 09 Apr 2010 10:31:27 +0800 Subject: [Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4. In-Reply-To: <4BBE8938.5000305@oracle.com> References: <1270724553-2621-1-git-send-email-tristan.ye@oracle.com> <4BBDEE98.8030005@oracle.com> <4BBE8938.5000305@oracle.com> Message-ID: <4BBE917F.5060506@oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com Hi Tristan, tristan wrote: > Tao, > > Thanks a lot for your quick review;) > > Tao Ma wrote: >> Hi Tristan, >> Tristan Ye wrote: >>> Changes from v3 to v4: >>> >>> 1. Fix a bug when crossing extent blocks. >>> >>> 2. Fix a bug when hole exists in the beginning of an extent block. >>> >>> 3. Apply tao's comments. >>> >>> >>> Signed-off-by: Tristan Ye >>> --- >>> fs/ocfs2/file.c | 233 >>> ++++++++++++++++++++++++++++++++++++++++++++++++------- >>> 1 files changed, 206 insertions(+), 27 deletions(-) >>> >>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c >>> index db2e0c9..75e087f 100644 >>> --- a/fs/ocfs2/file.c >>> +++ b/fs/ocfs2/file.c >>> @@ -1423,18 +1423,154 @@ out: >>> return ret; >>> } >>> >>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el, >>> + struct ocfs2_extent_rec **rec_found, >>> + u32 *pos) >>> +{ >>> + int i, found = 0; >>> + struct ocfs2_extent_rec *rec = NULL; >>> + >>> + for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) { >>> + >>> + rec = &el->l_recs[i]; >>> + >>> + if (le32_to_cpu(rec->e_cpos) <= *pos) { >>> + found = 1; >>> + break; >>> + } >>> + } >>> + >>> + if (!found) >>> + *rec_found = NULL; >>> + else >>> + *rec_found = &el->l_recs[i]; >>> +} >>> >> This function never returns pos now. So why you want to pass a *pos? >> another issue is that now it seems that you only want to returns a rec? >> then why not change this function to >> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos) > > Yes, it's confusing to use *pos, thanks for pointing this out. > >> and after the loop, just return i. So if i>=0, you find it, if i < 0, >> no rec is found. Looks more natural? > > I think returning a meaty record would be more straightforward. why? actually as I have said below, these 2 functions ocfs2_find_rec and ocfs2_find_rec_with_holes can be integrated into one function named ocfs2_find_rec or whatever. You are too nervous about holes actually. So static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos) { int i; struct ocfs2_extent_rec *rec = NULL; for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) { rec = &el->l_recs[i]; if (le32_to_cpu(rec->e_cpos) < pos) break; } return i; } And in the caller, you do(only the schema here): i = ocfs2_find_rec(el, pos); if (i > 0) { /* ok, we have to remove some clusters somehow. */ rec = &el->l_recs[i]; range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec); range = min(range, pos); ocfs2_calc_trunc_pos(); ocfs2_remove_btree_range(); /* Finished the work or we still have some more recs to punch. */ if (trunc_start == trunc_end) /* I don't know whether this check is right or not. */ break; i--; } if (i < 0) { /* ok, get to the next block, some calculation to find new pos. */ continue; } else cpos = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec); See the both functions looks more clean now. And your function ocfs2_find_rec_with_holes is a little complicated and so many comments to say why we want to do this. > >>> + >>> +/* >>> + * Hepler to find the rightmost record which contains 'pos' cpos, >>> + * skip the holes if any, also adjust the 'pos' accordingly. >>> + */ >>> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el, >>> + struct ocfs2_extent_rec **rec_found, >>> + u32 *pos) >>> +{ >>> + int i, found = 0; >>> + u32 range; >>> + struct ocfs2_extent_rec *rec = NULL; >>> + >>> + for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) { >>> + >>> + rec = &el->l_recs[i]; >>> + range = le32_to_cpu(rec->e_cpos) + >>> + ocfs2_rec_clusters(el, rec); >>> + >>> + if (le32_to_cpu(rec->e_cpos) < *pos) { >>> + /* >>> + * Skip a hole. >>> + */ >>> + if (range < *pos) >>> + *pos = range; >>> + >>> + found = 1; >>> + break; >>> + } >>> + >>> + /* >>> + * Simply jump to previous record if the pos is >>> + * the start of a record. >>> + */ >>> + if (le32_to_cpu(rec->e_cpos) == *pos) { >>> + i--; >>> + /* >>> + * The rec we're looking for is in previous >>> + * extent block. >>> + */ >>> + if (i < 0) >>> + break; >>> + >>> + rec = &el->l_recs[i]; >>> + range = le32_to_cpu(rec->e_cpos) + >>> + ocfs2_rec_clusters(el, rec); >>> + /* >>> + * Skip a hole. >>> + */ >>> + if (range < *pos) >>> + *pos = range; >>> >> As I have said in the previous e-mail, no matter whether there is a >> hole or not, we should set *pos = range since >> it will be the next 'end' we punch. And it looks more readable. >>> + >>> + found = 1; >>> + break; >>> + } >>> + } >>> + >>> + if (!found) >>> + *rec_found = NULL; >>> + else >>> + *rec_found = &el->l_recs[i]; >>> >> And the same for this function you can just return 'i' and I guess >> this function and the previous one can be integrated >> into just one. > > I don't think so, second function handles the hole and adjust the pos > accordingly, while second one only simply search the rec. > >>> +} >>> + >>> +/* >>> + * Helper to calculate the punching pos and length in one run, we >>> handle the >>> + * following three cases in order: >>> + * >>> + * - remove the entire record >>> + * - remove a partial record >>> + * - no record needs to be removed (hole-punching completed) >>> +*/ >>> +static void ocfs2_calc_trunc_pos(struct inode *inode, >>> + struct ocfs2_extent_list *el, >>> + struct ocfs2_extent_rec *rec, >>> + u32 trunc_start, u32 *trunc_cpos, >>> + u32 *trunc_len, u32 *trunc_end, >>> + u64 *blkno, int *done) >>> +{ >>> + int ret = 0; >>> + u32 coff, range; >>> + >>> + range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec); >>> + >>> + if (le32_to_cpu(rec->e_cpos) >= trunc_start) { >>> + *trunc_cpos = le32_to_cpu(rec->e_cpos); >>> + *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos); >>> + *blkno = le64_to_cpu(rec->e_blkno); >>> + *trunc_end = le32_to_cpu(rec->e_cpos); >>> + } else if (range > trunc_start) { >>> + *trunc_cpos = trunc_start; >>> + *trunc_len = range - trunc_start; >>> + coff = trunc_start - le32_to_cpu(rec->e_cpos); >>> + *blkno = le64_to_cpu(rec->e_blkno) + >>> + ocfs2_clusters_to_blocks(inode->i_sb, coff); >>> + *trunc_end = trunc_start; >>> + } else { >>> + /* >>> + * It may have two following possibilities: >>> + * >>> + * - last record has been removed >>> + * - trunc_start was within a hole >>> + * >>> + * both two cases mean the completion of hole punching. >>> + */ >>> + ret = 1; >>> + } >>> + >>> + *done = ret; >>> +} >>> + >>> static int ocfs2_remove_inode_range(struct inode *inode, >>> struct buffer_head *di_bh, u64 byte_start, >>> u64 byte_len) >>> { >>> - int ret = 0, flags = 0; >>> - u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size; >>> + int ret = 0, flags = 0, done = 0; >>> + u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos; >>> + u32 cluster_within_list; >>> struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); >>> struct ocfs2_cached_dealloc_ctxt dealloc; >>> struct address_space *mapping = inode->i_mapping; >>> struct ocfs2_extent_tree et; >>> + struct ocfs2_path *path = NULL; >>> + struct ocfs2_extent_list *el = NULL; >>> + struct ocfs2_extent_rec *rec = NULL; >>> struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data; >>> - u64 refcount_loc = le64_to_cpu(di->i_refcount_loc); >>> + u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc); >>> >>> ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh); >>> ocfs2_init_dealloc_ctxt(&dealloc); >>> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct >>> inode *inode, >>> } >>> >>> trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start); >>> - trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits; >>> - if (trunc_len >= trunc_start) >>> - trunc_len -= trunc_start; >>> - else >>> - trunc_len = 0; >>> + trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits; >>> + cluster_within_list = trunc_end; >>> >>> - mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: >>> %u\n", >>> + mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: >>> %u\n", >>> (unsigned long long)OCFS2_I(inode)->ip_blkno, >>> (unsigned long long)byte_start, >>> - (unsigned long long)byte_len, trunc_start, trunc_len); >>> + (unsigned long long)byte_len, trunc_start, trunc_end); >>> >>> ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len); >>> if (ret) { >>> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct >>> inode *inode, >>> goto out; >>> } >>> >>> - cpos = trunc_start; >>> - while (trunc_len) { >>> - ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, >>> - &alloc_size, &flags); >>> + path = ocfs2_new_path_from_et(&et); >>> + if (!path) { >>> + ret = -ENOMEM; >>> + mlog_errno(ret); >>> + goto out; >>> + } >>> + >>> + while (trunc_end > 0) { >>> >> I think we have a consensus to change this check somehow? > > Oh, that's correct, I hate to be a moron to forget updating this... > > >>> + /* >>> + * Unlike truncate codes, here we want to find a path which >>> + * contains (trunc_end - 1) cpos, and then trunc_end will be >>> + * decreased after each removal of a record range. >>> + * >>> + * Why not using trunc_end to search the path? >>> + * The reason is simple, think about the situation of crossing >>> + * the extent block, we need to find the adjacent block by >>> + * decreasing one cluster, otherwise, it will run into a loop. >>> + */ >>> + ret = ocfs2_find_path(INODE_CACHE(inode), path, >>> + cluster_within_list); >>> if (ret) { >>> mlog_errno(ret); >>> goto out; >>> } >>> >>> - if (alloc_size > trunc_len) >>> - alloc_size = trunc_len; >>> + el = path_leaf_el(path); >>> >>> - /* Only do work for non-holes */ >>> - if (phys_cpos != 0) { >>> - ret = ocfs2_remove_btree_range(inode, &et, cpos, >>> - phys_cpos, alloc_size, >>> - &dealloc, refcount_loc, >>> - flags); >>> - if (ret) { >>> - mlog_errno(ret); >>> - goto out; >>> + ocfs2_find_rec_with_holes(el, &rec, &trunc_end); >>> + /* >>> + * Need to go to previous extent block. >>> + */ >>> + if (!rec) { >>> + if (path->p_tree_depth == 0) >>> + break; >>> + else { >>> + el = path->p_node[path->p_tree_depth - 1].el; >>> + ocfs2_find_rec(el, &rec, &trunc_end); >>> + if (!rec) >>> + break; >>> + if (le32_to_cpu(rec->e_cpos)) { >>> + trunc_end = le32_to_cpu(rec->e_cpos); >>> + cluster_within_list = trunc_end - 1; >>> + } else >>> + break; >>> } >>> >> oh, I really see what you are going to do here. It is really buggy. >> What if the tree_depth=2, and the branch >> extent block with 'tree_depth-1' is also recs[0] in the tree_depth >> extent block? you can't find 'rec' and break. >> Actually there is already a function. ;) Check >> ocfs2_find_cpos_for_left_leaf for detail. > > Sorry, I can't get your idea clearly, what did you mean 'the branch > extent block with 'tree_depth-1' is also recs[0] in the tree_depth > extent block?', how does that matter? why can't I find the 'rec' here? > > Per my understanding, when we found the hole before first rec in leaf > extent block, we need to go back to its father extent block through path > where no hole existed for sure. and we definitely find the rec there. Check ocfs2_find_cpos_for_left_leaf. It has done what you want already. Regards, Tao