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Message-ID: <4D841D34.3020101@linux.vnet.ibm.com>
Date: Fri, 18 Mar 2011 20:04:20 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org
Subject: [Ext4 punch hole 3/4 v4] Ext4 Punch Hole Support: Punch out extents
This patch modifies the truncate routines to support hole punching
Below is a brief summary of the patches changes:
- Added end param to ext_ext4_rm_leaf
This function has been modified to accept an end parameter
which enables it to punch holes in leafs instead of just
truncating them.
- Implemented the "remove head" case in the ext_remove_blocks routine
This routine is used by ext_ext4_rm_leaf to remove the tail
of an extent during a truncate. The new ext_ext4_rm_leaf
routine will now also use it to remove the head of an extent in the
case that the hole covers a region of blocks at the beginning
of an extent.
- Added "end" param to ext4_ext_remove_space routine
This function has been modified to accept a stop parameter, which
is passed through to ext4_ext_rm_leaf.
Signed-off-by: Allison Henderson <achender@...ibm.com>
---
:100644 100644 b78b41f... 01a83a1... M fs/ext4/extents.c
fs/ext4/extents.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 126 insertions(+), 19 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b78b41f..01a83a1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2159,8 +2159,16 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
ext4_free_blocks(handle, inode, NULL, start, num, flags);
} else if (from == le32_to_cpu(ex->ee_block)
&& to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
- printk(KERN_INFO "strange request: removal %u-%u from %u:%u\n",
- from, to, le32_to_cpu(ex->ee_block), ee_len);
+ /* head removal */
+ ext4_lblk_t num;
+ ext4_fsblk_t start;
+
+ num = to - from;
+ start = ext4_ext_pblock(ex);
+
+ ext_debug("free first %u blocks starting %llu\n", num, start);
+ ext4_free_blocks(handle, inode, 0, start, num, flags);
+
} else {
printk(KERN_INFO "strange request: removal(2) "
"%u-%u from %u:%u\n",
@@ -2272,9 +2280,22 @@ fix_extent_len:
return err;
}
+
+/*
+ * ext4_ext_rm_leaf() Removes the extents associated with the
+ * blocks appearing between "start" and "end", and splits the extents
+ * if "start" and "end" appear in the same extent
+ *
+ * @handle: The journal handle
+ * @inode: The files inode
+ * @path: The path to the leaf
+ * @start: The first block to remove
+ * @end: The last block to remove
+ */
static int
ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
- struct ext4_ext_path *path, ext4_lblk_t start)
+ struct ext4_ext_path *path, ext4_lblk_t start,
+ ext4_lblk_t end)
{
int err = 0, correct_index = 0;
int depth = ext_depth(inode), credits;
@@ -2314,31 +2335,88 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
path[depth].p_ext = ex;
a = ex_ee_block > start ? ex_ee_block : start;
- b = ex_ee_block + ex_ee_len - 1 < EXT_MAX_BLOCK ?
- ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;
+ b = ex_ee_block+ex_ee_len - 1 < end ?
+ ex_ee_block+ex_ee_len - 1 : end;
ext_debug(" border %u:%u\n", a, b);
- if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
- block = 0;
- num = 0;
- BUG();
+ /* If this extent is beyond the end of the hole, skip it */
+ if (end <= ex_ee_block) {
+ ex--;
+ ex_ee_block = le32_to_cpu(ex->ee_block);
+ ex_ee_len = ext4_ext_get_actual_len(ex);
+ continue;
+ } else if (a != ex_ee_block &&
+ b != ex_ee_block + ex_ee_len - 1) {
+ /*
+ * If this is a truncate, then this condition should
+ * never happen because at least one of the end points
+ * needs to be on the edge of the extent.
+ */
+ if (end == EXT_MAX_BLOCK) {
+ ext_debug(" bad truncate %u:%u\n",
+ start, end);
+ block = 0;
+ num = 0;
+ err = -EIO;
+ goto out;
+ }
+ /*
+ * else this is a hole punch, so the extent needs to
+ * be split since neither edge of the hole is on the
+ * extent edge
+ */
+ else{
+ err = ext4_split_extents(handle, inode,
+ b, path, 0);
+ if (err)
+ goto out;
+
+ ex_ee_len = ext4_ext_get_actual_len(ex);
+
+ b = ex_ee_block+ex_ee_len - 1 < end ?
+ ex_ee_block+ex_ee_len - 1 : end;
+
+ /* Then remove tail of this extent */
+ block = ex_ee_block;
+ num = a - block;
+ }
} else if (a != ex_ee_block) {
/* remove tail of the extent */
block = ex_ee_block;
num = a - block;
} else if (b != ex_ee_block + ex_ee_len - 1) {
/* remove head of the extent */
- block = a;
- num = b - a;
- /* there is no "make a hole" API yet */
- BUG();
+ block = b;
+ num = ex_ee_block + ex_ee_len - b;
+
+ /*
+ * If this is a truncate, this condition
+ * should never happen
+ */
+ if (end == EXT_MAX_BLOCK) {
+ ext_debug(" bad truncate %u:%u\n",
+ start, end);
+ err = -EIO;
+ goto out;
+ }
} else {
/* remove whole extent: excellent! */
block = ex_ee_block;
num = 0;
- BUG_ON(a != ex_ee_block);
- BUG_ON(b != ex_ee_block + ex_ee_len - 1);
+ if (a != ex_ee_block) {
+ ext_debug(" bad truncate %u:%u\n",
+ start, end);
+ err = -EIO;
+ goto out;
+ }
+
+ if (b != ex_ee_block + ex_ee_len - 1) {
+ ext_debug(" bad truncate %u:%u\n",
+ start, end);
+ err = -EIO;
+ goto out;
+ }
}
/*
@@ -2369,7 +2447,13 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
if (num == 0) {
/* this extent is removed; mark slot entirely unused */
ext4_ext_store_pblock(ex, 0);
- le16_add_cpu(&eh->eh_entries, -1);
+ } else if (block != ex_ee_block) {
+ /*
+ * If this was a head removal, then we need to update
+ * the physical block since it is now at a different
+ * location
+ */
+ ext4_ext_store_pblock(ex, ext4_ext_pblock(ex) + (b-a));
}
ex->ee_block = cpu_to_le32(block);
@@ -2385,6 +2469,27 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
if (err)
goto out;
+ /*
+ * If the extent was completely released,
+ * we need to remove it from the leaf
+ */
+ if (num == 0) {
+ if (end != EXT_MAX_BLOCK) {
+ /*
+ * For hole punching, we need to scoot all the
+ * extents up when an extent is removed so that
+ * we dont have blank extents in the middle
+ */
+ memmove(ex, ex+1, (EXT_LAST_EXTENT(eh) - ex) *
+ sizeof(struct ext4_extent));
+
+ /* Now get rid of the one at the end */
+ memset(EXT_LAST_EXTENT(eh), 0,
+ sizeof(struct ext4_extent));
+ }
+ le16_add_cpu(&eh->eh_entries, -1);
+ }
+
ext_debug("new extent: %u:%u:%llu\n", block, num,
ext4_ext_pblock(ex));
ex--;
@@ -2425,7 +2530,8 @@ ext4_ext_more_to_rm(struct ext4_ext_path *path)
return 1;
}
-static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
+static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
+ ext4_lblk_t end)
{
struct super_block *sb = inode->i_sb;
int depth = ext_depth(inode);
@@ -2464,7 +2570,8 @@ again:
while (i >= 0 && err == 0) {
if (i == depth) {
/* this is leaf block */
- err = ext4_ext_rm_leaf(handle, inode, path, start);
+ err = ext4_ext_rm_leaf(handle, inode, path,
+ start, end);
/* root level has p_bh == NULL, brelse() eats this */
brelse(path[i].p_bh);
path[i].p_bh = NULL;
@@ -3676,7 +3783,7 @@ void ext4_ext_truncate(struct inode *inode)
last_block = (inode->i_size + sb->s_blocksize - 1)
>> EXT4_BLOCK_SIZE_BITS(sb);
- err = ext4_ext_remove_space(inode, last_block);
+ err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCK);
/* In a multi-transaction truncate, we only make the final
* transaction synchronous.
--
1.7.1
--
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