Messages in this thread | | | From | Changwei Ge <> | Subject | Re: [Ocfs2-devel] [PATCH 2/3] ocfs2: add ocfs2_overwrite_io function | Date | Tue, 28 Nov 2017 02:10:20 +0000 |
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On 2017/11/28 9:52, piaojun wrote: > Hi Gang, > > If ocfs2_overwrite_io is only called in 'nowait' scenarios, I wonder if > we can discard 'int wait' just as ext4 does: > > static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len);
Yes, Jun has a point. It seems that ocfs2_overwrite_io is only involved in non-blocking aio and no other code spot is calling ocfs2_overwrite_io with wait=1 passed.
> > thans, > Jun > > On 2017/11/27 17:46, Gang He wrote: >> Add ocfs2_overwrite_io function, which is used to judge if >> overwrite allocated blocks, otherwise, the write will bring extra >> block allocation overhead. >> >> Signed-off-by: Gang He <ghe@suse.com> >> --- >> fs/ocfs2/extent_map.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ >> fs/ocfs2/extent_map.h | 3 +++ >> 2 files changed, 70 insertions(+) >> >> diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c >> index e4719e0..98bf325 100644 >> --- a/fs/ocfs2/extent_map.c >> +++ b/fs/ocfs2/extent_map.c >> @@ -832,6 +832,73 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> return ret; >> } >> >> +/* Is IO overwriting allocated blocks? */ >> +int ocfs2_overwrite_io(struct inode *inode, u64 map_start, u64 map_len, >> + int wait) >> +{ >> + int ret = 0, is_last; >> + u32 mapping_end, cpos; >> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); >> + struct buffer_head *di_bh = NULL; >> + struct ocfs2_extent_rec rec; >> + >> + if (wait) >> + ret = ocfs2_inode_lock(inode, &di_bh, 0); >> + else >> + ret = ocfs2_try_inode_lock(inode, &di_bh, 0); >> + if (ret) >> + goto out; >> + >> + if (wait) >> + down_read(&OCFS2_I(inode)->ip_alloc_sem); >> + else { >> + if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) { >> + ret = -EAGAIN; Here is a little strange, it seems that you don't care much about how this function fails. Why evaluate _ret_ to -EAGAIN here and ignore it later?
Thanks, Changwei
>> + goto out_unlock1; >> + } >> + } >> + >> + if ((OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) && >> + ((map_start + map_len) <= i_size_read(inode))) >> + goto out_unlock2; >> + >> + cpos = map_start >> osb->s_clustersize_bits; >> + mapping_end = ocfs2_clusters_for_bytes(inode->i_sb, >> + map_start + map_len); >> + is_last = 0; >> + while (cpos < mapping_end && !is_last) { >> + ret = ocfs2_get_clusters_nocache(inode, di_bh, cpos, >> + NULL, &rec, &is_last); >> + if (ret) { >> + mlog_errno(ret); >> + goto out_unlock2; >> + } >> + >> + if (rec.e_blkno == 0ULL) >> + break; >> + >> + if (rec.e_flags & OCFS2_EXT_REFCOUNTED) >> + break; >> + >> + cpos = le32_to_cpu(rec.e_cpos) + >> + le16_to_cpu(rec.e_leaf_clusters); >> + } >> + >> + if (cpos < mapping_end) >> + ret = 1; >> + >> +out_unlock2: >> + brelse(di_bh); >> + >> + up_read(&OCFS2_I(inode)->ip_alloc_sem); >> + >> +out_unlock1: >> + ocfs2_inode_unlock(inode, 0); >> + >> +out: >> + return (ret ? 0 : 1); >> +} >> + >> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int whence) >> { >> struct inode *inode = file->f_mapping->host; >> diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h >> index 67ea57d..fd9e86a 100644 >> --- a/fs/ocfs2/extent_map.h >> +++ b/fs/ocfs2/extent_map.h >> @@ -53,6 +53,9 @@ int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno, >> int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> u64 map_start, u64 map_len); >> >> +int ocfs2_overwrite_io(struct inode *inode, u64 map_start, u64 map_len, >> + int wait); >> + >> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin); >> >> int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster, >> > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel@oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel >
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