[PATCH 4/5] ext4: fallocate support in ext4

Amit K. Arora
2007-04-26T18:58:08Z

This patch has the ext4 implemtation of fallocate system call.

Signed-off-by: Amit Arora <aarora@in.ibm.com>
---
fs/ext4/extents.c | 201 +++++++++++++++++++++++++++++++---------
fs/ext4/file.c | 1
include/linux/ext4_fs.h | 7 +
include/linux/ext4_fs_extents.h | 13 ++
4 files changed, 179 insertions(+), 43 deletions(-)

Index: linux-2.6.21/fs/ext4/extents.c
===================================================================
--- linux-2.6.21.orig/fs/ext4/extents.c
+++ linux-2.6.21/fs/ext4/extents.c
@@ -283,7 +283,7 @@ static void ext4_ext_show_path(struct in
} else if (path->p_ext) {
ext_debug(" %d:%d:%llu ",
le32_to_cpu(path->p_ext->ee_block),
- le16_to_cpu(path->p_ext->ee_len),
+ ext4_ext_get_actual_len(path->p_ext),
ext_pblock(path->p_ext));
} else
ext_debug(" []");
@@ -306,7 +306,7 @@ static void ext4_ext_show_leaf(struct in

for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
ext_debug("%d:%d:%llu ", le32_to_cpu(ex->ee_block),
- le16_to_cpu(ex->ee_len), ext_pblock(ex));
+ ext4_ext_get_actual_len(ex), ext_pblock(ex));
}
ext_debug("\n");
}
@@ -426,7 +426,7 @@ ext4_ext_binsearch(struct inode *inode,
ext_debug(" -> %d:%llu:%d ",
le32_to_cpu(path->p_ext->ee_block),
ext_pblock(path->p_ext),
- le16_to_cpu(path->p_ext->ee_len));
+ ext4_ext_get_actual_len(path->p_ext));

#ifdef CHECK_BINSEARCH
{
@@ -687,7 +687,7 @@ static int ext4_ext_split(handle_t *hand
ext_debug("move %d:%llu:%d in new leaf %llu\n",
le32_to_cpu(path[depth].p_ext->ee_block),
ext_pblock(path[depth].p_ext),
- le16_to_cpu(path[depth].p_ext->ee_len),
+ ext4_ext_get_actual_len(path[depth].p_ext),
newblock);
/*memmove(ex++, path[depth].p_ext++,
sizeof(struct ext4_extent));
@@ -1107,7 +1107,19 @@ static int
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
struct ext4_extent *ex2)
{
- if (le32_to_cpu(ex1->ee_block) + le16_to_cpu(ex1->ee_len) !=
+ unsigned short ext1_ee_len, ext2_ee_len;
+
+ /*
+ * Make sure that either both extents are uninitialized, or
+ * both are _not_.
+ */
+ if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
+ return 0;
+
+ ext1_ee_len = ext4_ext_get_actual_len(ex1);
+ ext2_ee_len = ext4_ext_get_actual_len(ex2);
+
+ if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
le32_to_cpu(ex2->ee_block))
return 0;

@@ -1116,14 +1128,14 @@ ext4_can_extents_be_merged(struct inode
* as an RO_COMPAT feature, refuse to merge to extents if
* this can result in the top bit of ee_len being set.
*/
- if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
+ if (ext1_ee_len + ext2_ee_len > EXT_MAX_LEN)
return 0;
#ifdef AGGRESSIVE_TEST
if (le16_to_cpu(ex1->ee_len) >= 4)
return 0;
#endif

- if (ext_pblock(ex1) + le16_to_cpu(ex1->ee_len) == ext_pblock(ex2))
+ if (ext_pblock(ex1) + ext1_ee_len == ext_pblock(ex2))
return 1;
return 0;
}
@@ -1145,7 +1157,7 @@ unsigned int ext4_ext_check_overlap(stru
unsigned int depth, len1;

b1 = le32_to_cpu(newext->ee_block);
- len1 = le16_to_cpu(newext->ee_len);
+ len1 = ext4_ext_get_actual_len(newext);
depth = ext_depth(inode);
if (!path[depth].p_ext)
goto out;
@@ -1181,9 +1193,9 @@ int ext4_ext_insert_extent(handle_t *han
struct ext4_extent *ex, *fex;
struct ext4_extent *nearex; /* nearest extent */
struct ext4_ext_path *npath = NULL;
- int depth, len, err, next;
+ int depth, len, err, next, uninitialized = 0;

- BUG_ON(newext->ee_len == 0);
+ BUG_ON(ext4_ext_get_actual_len(newext) == 0);
depth = ext_depth(inode);
ex = path[depth].p_ext;
BUG_ON(path[depth].p_hdr == NULL);
@@ -1191,14 +1203,23 @@ int ext4_ext_insert_extent(handle_t *han
/* try to insert block into found extent and return */
if (ex && ext4_can_extents_be_merged(inode, ex, newext)) {
ext_debug("append %d block to %d:%d (from %llu)\n",
- le16_to_cpu(newext->ee_len),
+ ext4_ext_get_actual_len(newext),
le32_to_cpu(ex->ee_block),
- le16_to_cpu(ex->ee_len), ext_pblock(ex));
+ ext4_ext_get_actual_len(ex), ext_pblock(ex));
err = ext4_ext_get_access(handle, inode, path + depth);
if (err)
return err;
- ex->ee_len = cpu_to_le16(le16_to_cpu(ex->ee_len)
- + le16_to_cpu(newext->ee_len));
+
+ /* ext4_can_extents_be_merged should have checked that either
+ * both extents are uninitialized, or both aren't. Thus we
+ * need to check only one of them here.
+ */
+ if (ext4_ext_is_uninitialized(ex))
+ uninitialized = 1;
+ ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+ + ext4_ext_get_actual_len(newext));
+ if (uninitialized)
+ ext4_ext_mark_uninitialized(ex);
eh = path[depth].p_hdr;
nearex = ex;
goto merge;
@@ -1254,7 +1275,7 @@ has_space:
ext_debug("first extent in the leaf: %d:%llu:%d\n",
le32_to_cpu(newext->ee_block),
ext_pblock(newext),
- le16_to_cpu(newext->ee_len));
+ ext4_ext_get_actual_len(newext));
path[depth].p_ext = EXT_FIRST_EXTENT(eh);
} else if (le32_to_cpu(newext->ee_block)
> le32_to_cpu(nearex->ee_block)) {
@@ -1267,7 +1288,7 @@ has_space:
"move %d from 0x%p to 0x%p\n",
le32_to_cpu(newext->ee_block),
ext_pblock(newext),
- le16_to_cpu(newext->ee_len),
+ ext4_ext_get_actual_len(newext),
nearex, len, nearex + 1, nearex + 2);
memmove(nearex + 2, nearex + 1, len);
}
@@ -1280,7 +1301,7 @@ has_space:
"move %d from 0x%p to 0x%p\n",
le32_to_cpu(newext->ee_block),
ext_pblock(newext),
- le16_to_cpu(newext->ee_len),
+ ext4_ext_get_actual_len(newext),
nearex, len, nearex + 1, nearex + 2);
memmove(nearex + 1, nearex, len);
path[depth].p_ext = nearex;
@@ -1299,8 +1320,13 @@ merge:
if (!ext4_can_extents_be_merged(inode, nearex, nearex + 1))
break;
/* merge with next extent! */
- nearex->ee_len = cpu_to_le16(le16_to_cpu(nearex->ee_len)
- + le16_to_cpu(nearex[1].ee_len));
+ if (ext4_ext_is_uninitialized(nearex))
+ uninitialized = 1;
+ nearex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(nearex)
+ + ext4_ext_get_actual_len(nearex + 1));
+ if (uninitialized)
+ ext4_ext_mark_uninitialized(nearex);
+
if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
len = (EXT_LAST_EXTENT(eh) - nearex - 1)
* sizeof(struct ext4_extent);
@@ -1370,8 +1396,8 @@ int ext4_ext_walk_space(struct inode *in
end = le32_to_cpu(ex->ee_block);
if (block + num < end)
end = block + num;
- } else if (block >=
- le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len)) {
+ } else if (block >= le32_to_cpu(ex->ee_block)
+ + ext4_ext_get_actual_len(ex)) {
/* need to allocate space after found extent */
start = block;
end = block + num;
@@ -1383,7 +1409,8 @@ int ext4_ext_walk_space(struct inode *in
* by found extent
*/
start = block;
- end = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len);
+ end = le32_to_cpu(ex->ee_block)
+ + ext4_ext_get_actual_len(ex);
if (block + num < end)
end = block + num;
exists = 1;
@@ -1399,7 +1426,7 @@ int ext4_ext_walk_space(struct inode *in
cbex.ec_type = EXT4_EXT_CACHE_GAP;
} else {
cbex.ec_block = le32_to_cpu(ex->ee_block);
- cbex.ec_len = le16_to_cpu(ex->ee_len);
+ cbex.ec_len = ext4_ext_get_actual_len(ex);
cbex.ec_start = ext_pblock(ex);
cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
}
@@ -1472,15 +1499,15 @@ ext4_ext_put_gap_in_cache(struct inode *
ext_debug("cache gap(before): %lu [%lu:%lu]",
(unsigned long) block,
(unsigned long) le32_to_cpu(ex->ee_block),
- (unsigned long) le16_to_cpu(ex->ee_len));
+ (unsigned long) ext4_ext_get_actual_len(ex));
} else if (block >= le32_to_cpu(ex->ee_block)
- + le16_to_cpu(ex->ee_len)) {
+ + ext4_ext_get_actual_len(ex)) {
lblock = le32_to_cpu(ex->ee_block)
- + le16_to_cpu(ex->ee_len);
+ + ext4_ext_get_actual_len(ex);
len = ext4_ext_next_allocated_block(path);
ext_debug("cache gap(after): [%lu:%lu] %lu",
(unsigned long) le32_to_cpu(ex->ee_block),
- (unsigned long) le16_to_cpu(ex->ee_len),
+ (unsigned long) ext4_ext_get_actual_len(ex),
(unsigned long) block);
BUG_ON(len == lblock);
len = len - lblock;
@@ -1610,12 +1637,12 @@ static int ext4_remove_blocks(handle_t *
unsigned long from, unsigned long to)
{
struct buffer_head *bh;
+ unsigned short ee_len = ext4_ext_get_actual_len(ex);
int i;

#ifdef EXTENTS_STATS
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
- unsigned short ee_len = le16_to_cpu(ex->ee_len);
spin_lock(&sbi->s_ext_stats_lock);
sbi->s_ext_blocks += ee_len;
sbi->s_ext_extents++;
@@ -1629,12 +1656,12 @@ static int ext4_remove_blocks(handle_t *
}
#endif
if (from >= le32_to_cpu(ex->ee_block)
- && to == le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
+ && to == le32_to_cpu(ex->ee_block) + ee_len - 1) {
/* tail removal */
unsigned long num;
ext4_fsblk_t start;
- num = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - from;
- start = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - num;
+ num = le32_to_cpu(ex->ee_block) + ee_len - from;
+ start = ext_pblock(ex) + ee_len - num;
ext_debug("free last %lu blocks starting %llu\n", num, start);
for (i = 0; i < num; i++) {
bh = sb_find_get_block(inode->i_sb, start + i);
@@ -1642,12 +1669,12 @@ static int ext4_remove_blocks(handle_t *
}
ext4_free_blocks(handle, inode, start, num);
} else if (from == le32_to_cpu(ex->ee_block)
- && to <= le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
+ && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
printk("strange request: removal %lu-%lu from %u:%u\n",
- from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
+ from, to, le32_to_cpu(ex->ee_block), ee_len);
} else {
printk("strange request: removal(2) %lu-%lu from %u:%u\n",
- from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
+ from, to, le32_to_cpu(ex->ee_block), ee_len);
}
return 0;
}
@@ -1661,7 +1688,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
struct ext4_extent_header *eh;
unsigned a, b, block, num;
unsigned long ex_ee_block;
- unsigned short ex_ee_len;
+ unsigned short ex_ee_len, uninitialized = 0;
struct ext4_extent *ex;

ext_debug("truncate since %lu in leaf\n", start);
@@ -1676,7 +1703,9 @@ ext4_ext_rm_leaf(handle_t *handle, struc
ex = EXT_LAST_EXTENT(eh);

ex_ee_block = le32_to_cpu(ex->ee_block);
- ex_ee_len = le16_to_cpu(ex->ee_len);
+ if (ext4_ext_is_uninitialized(ex))
+ uninitialized = 1;
+ ex_ee_len = ext4_ext_get_actual_len(ex);

while (ex >= EXT_FIRST_EXTENT(eh) &&
ex_ee_block + ex_ee_len > start) {
@@ -1744,6 +1773,8 @@ ext4_ext_rm_leaf(handle_t *handle, struc

ex->ee_block = cpu_to_le32(block);
ex->ee_len = cpu_to_le16(num);
+ if (uninitialized)
+ ext4_ext_mark_uninitialized(ex);

err = ext4_ext_dirty(handle, inode, path + depth);
if (err)
@@ -1753,7 +1784,7 @@ ext4_ext_rm_leaf(handle_t *handle, struc
ext_pblock(ex));
ex--;
ex_ee_block = le32_to_cpu(ex->ee_block);
- ex_ee_len = le16_to_cpu(ex->ee_len);
+ ex_ee_len = ext4_ext_get_actual_len(ex);
}

if (correct_index && eh->eh_entries)
@@ -2029,7 +2060,7 @@ int ext4_ext_get_blocks(handle_t *handle
if (ex) {
unsigned long ee_block = le32_to_cpu(ex->ee_block);
ext4_fsblk_t ee_start = ext_pblock(ex);
- unsigned short ee_len = le16_to_cpu(ex->ee_len);
+ unsigned short ee_len;

/*
* Allow future support for preallocated extents to be added
@@ -2037,8 +2068,9 @@ int ext4_ext_get_blocks(handle_t *handle
* Uninitialized extents are treated as holes, except that
* we avoid (fail) allocating new blocks during a write.
*/
- if (ee_len > EXT_MAX_LEN)
+ if (le16_to_cpu(ex->ee_len) > EXT_MAX_LEN)
goto out2;
+ ee_len = ext4_ext_get_actual_len(ex);
/* if found extent covers block, simply return it */
if (iblock >= ee_block && iblock < ee_block + ee_len) {
newblock = iblock - ee_block + ee_start;
@@ -2046,8 +2078,11 @@ int ext4_ext_get_blocks(handle_t *handle
allocated = ee_len - (iblock - ee_block);
ext_debug("%d fit into %lu:%d -> %llu\n", (int) iblock,
ee_block, ee_len, newblock);
- ext4_ext_put_in_cache(inode, ee_block, ee_len,
- ee_start, EXT4_EXT_CACHE_EXTENT);
+ /* Do not put uninitialized extent in the cache */
+ if (!ext4_ext_is_uninitialized(ex))
+ ext4_ext_put_in_cache(inode, ee_block,
+ ee_len, ee_start,
+ EXT4_EXT_CACHE_EXTENT);
goto out;
}
}
@@ -2089,6 +2124,8 @@ int ext4_ext_get_blocks(handle_t *handle
/* try to insert new extent into found leaf and return */
ext4_ext_store_pblock(&newex, newblock);
newex.ee_len = cpu_to_le16(allocated);
+ if (create == EXT4_CREATE_UNINITIALIZED_EXT) /* Mark uninitialized */
+ ext4_ext_mark_uninitialized(&newex);
err = ext4_ext_insert_extent(handle, inode, path, &newex);
if (err)
goto out2;
@@ -2100,8 +2137,10 @@ int ext4_ext_get_blocks(handle_t *handle
newblock = ext_pblock(&newex);
__set_bit(BH_New, &bh_result->b_state);

- ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
- EXT4_EXT_CACHE_EXTENT);
+ /* Cache only when it is _not_ an uninitialized extent */
+ if (create!=EXT4_CREATE_UNINITIALIZED_EXT)
+ ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
+ EXT4_EXT_CACHE_EXTENT);
out:
if (allocated > max_blocks)
allocated = max_blocks;
@@ -2205,10 +2244,86 @@ int ext4_ext_writepage_trans_blocks(stru
return needed;
}

+/*
+ * ext4_fallocate:
+ * preallocate space for a file
+ * mode is for future use, e.g. for unallocating preallocated blocks etc.
+ */
+int ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
+{
+ handle_t *handle;
+ ext4_fsblk_t block, max_blocks;
+ int ret, ret2, nblocks = 0, retries = 0;
+ struct buffer_head map_bh;
+ unsigned int credits, blkbits = inode->i_blkbits;
+
+ /* Currently supporting (pre)allocate mode _only_ */
+ if (mode != FA_ALLOCATE)
+ return -EOPNOTSUPP;
+
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+ return -ENOTTY;
+
+ block = offset >> blkbits;
+ max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
+ - block;
+ mutex_lock(&EXT4_I(inode)->truncate_mutex);
+ credits = ext4_ext_calc_credits_for_insert(inode, NULL);
+ mutex_unlock(&EXT4_I(inode)->truncate_mutex);
+ handle=ext4_journal_start(inode, credits +
+ EXT4_DATA_TRANS_BLOCKS(inode->i_sb)+1);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+retry:
+ ret = 0;
+ while (ret >= 0 && ret < max_blocks) {
+ block = block + ret;
+ max_blocks = max_blocks - ret;
+ ret = ext4_ext_get_blocks(handle, inode, block,
+ max_blocks, &map_bh,
+ EXT4_CREATE_UNINITIALIZED_EXT, 0);
+ BUG_ON(!ret);
+ if (ret > 0 && test_bit(BH_New, &map_bh.b_state)
+ && ((block + ret) > (i_size_read(inode) << blkbits)))
+ nblocks = nblocks + ret;
+ }
+
+ if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;
+
+ /* Time to update the file size.
+ * Update only when preallocation was requested beyond the file size.
+ */
+ if ((offset + len) > i_size_read(inode)) {
+ if (ret > 0) {
+ /* if no error, we assume preallocation succeeded completely */
+ mutex_lock(&inode->i_mutex);
+ i_size_write(inode, offset + len);
+ EXT4_I(inode)->i_disksize = i_size_read(inode);
+ mutex_unlock(&inode->i_mutex);
+ } else if (ret < 0 && nblocks) {
+ /* Handle partial allocation scenario */
+ loff_t newsize;
+ mutex_lock(&inode->i_mutex);
+ newsize = (nblocks << blkbits) + i_size_read(inode);
+ i_size_write(inode, EXT4_BLOCK_ALIGN(newsize, blkbits));
+ EXT4_I(inode)->i_disksize = i_size_read(inode);
+ mutex_unlock(&inode->i_mutex);
+ }
+ }
+ ext4_mark_inode_dirty(handle, inode);
+ ret2 = ext4_journal_stop(handle);
+ if (ret > 0)
+ ret = ret2;
+
+ return ret > 0 ? 0 : ret;
+}
+
EXPORT_SYMBOL(ext4_mark_inode_dirty);
EXPORT_SYMBOL(ext4_ext_invalidate_cache);
EXPORT_SYMBOL(ext4_ext_insert_extent);
EXPORT_SYMBOL(ext4_ext_walk_space);
EXPORT_SYMBOL(ext4_ext_find_goal);
EXPORT_SYMBOL(ext4_ext_calc_credits_for_insert);
+EXPORT_SYMBOL(ext4_fallocate);

Index: linux-2.6.21/fs/ext4/file.c
===================================================================
--- linux-2.6.21.orig/fs/ext4/file.c
+++ linux-2.6.21/fs/ext4/file.c
@@ -135,5 +135,6 @@ const struct inode_operations ext4_file_
.removexattr = generic_removexattr,
#endif
.permission = ext4_permission,
+ .fallocate = ext4_fallocate,
};

Index: linux-2.6.21/include/linux/ext4_fs.h
===================================================================
--- linux-2.6.21.orig/include/linux/ext4_fs.h
+++ linux-2.6.21/include/linux/ext4_fs.h
@@ -102,6 +102,8 @@
EXT4_GOOD_OLD_FIRST_INO : \
(s)->s_first_ino)
#endif
+#define EXT4_BLOCK_ALIGN(size, blkbits) (((size)+(1 << blkbits)-1) & \
+ (~((1 << blkbits)-1)))

/*
* Macro-instructions used to manage fragments
@@ -225,6 +227,10 @@ struct ext4_new_group_data {
__u32 free_blocks_count;
};

+/* Following is used by preallocation logic to tell get_blocks() that we
+ * want uninitialzed extents.
+ */
+#define EXT4_CREATE_UNINITIALIZED_EXT 2

/*
* ioctl commands
@@ -976,6 +982,7 @@ extern int ext4_ext_get_blocks(handle_t
extern void ext4_ext_truncate(struct inode *, struct page *);
extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
+extern int ext4_fallocate(struct inode *, int, loff_t, loff_t);
static inline int
ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
unsigned long max_blocks, struct buffer_head *bh,
Index: linux-2.6.21/include/linux/ext4_fs_extents.h
===================================================================
--- linux-2.6.21.orig/include/linux/ext4_fs_extents.h
+++ linux-2.6.21/include/linux/ext4_fs_extents.h
@@ -125,6 +125,19 @@ struct ext4_ext_path {
#define EXT4_EXT_CACHE_EXTENT 2

/*
+ * Macro-instructions to handle (mark/unmark/check/create) unitialized
+ * extents. Applications can issue an IOCTL for preallocation, which results
+ * in assigning unitialized extents to the file.
+ */
+#define ext4_ext_mark_uninitialized(ext) ((ext)->ee_len |= \
+ cpu_to_le16(0x8000))
+#define ext4_ext_is_uninitialized(ext) ((le16_to_cpu((ext)->ee_len))& \
+ 0x8000)
+#define ext4_ext_get_actual_len(ext) ((le16_to_cpu((ext)->ee_len))& \
+ 0x7FFF)
+
+
+/*
* to be called by ext4_ext_walk_space()
* negative retcode - error
* positive retcode - signal for ext4_ext_walk_space(), see below