Re: [RFC][PATCH 3/9 v1] ext4: add physical block and status member into extent status tree
From: Jan Kara <jack@suse.cz>
Date: 2012-12-31 21:49:55
On Mon 24-12-12 15:55:36, Zheng Liu wrote:
From: Zheng Liu <redacted> es_pblk is used to record physical block that maps to the disk. es_status is used to record the status of the extent. Three status are defined, which are written, unwritten and delayed.
So this means one extent is 48 bytes on 64-bit architectures. If I'm a nasty user and create artificially fragmented file (by allocating every second block), extent tree takes 6 MB per GB of file. That's quite a bit and I think you need to provide a way for kernel to reclaim extent structures... Honza
quoted hunk ↗ jump to hunk
Signed-off-by: Zheng Liu <redacted> --- fs/ext4/extents_status.h | 8 ++++++++ 1 file changed, 8 insertions(+)diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h index 81e9339..85115bb 100644 --- a/fs/ext4/extents_status.h +++ b/fs/ext4/extents_status.h@@ -20,10 +20,18 @@ #define es_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__) #endif +enum { + EXTENT_STATUS_WRITTEN = 0, /* written extent */ + EXTENT_STATUS_UNWRITTEN = 1, /* unwritten extent */ + EXTENT_STATUS_DELAYED = 2, /* delayed extent */ +}; + struct extent_status { struct rb_node rb_node; ext4_lblk_t es_lblk; /* first logical block extent covers */ ext4_lblk_t es_len; /* length of extent in block */ + ext4_fsblk_t es_pblk; /* first physical block */ + int es_status; /* record the status of extent */ }; struct ext4_es_tree {-- 1.7.12.rc2.18.g61b472e -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Jan Kara [off-list ref] SUSE Labs, CR