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scoutfs: satisfy large allocs with smaller extents

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The previous fallocate and get_block allocators only looked for free
extents larger than the requested allocation size.  This prematurely
returns -ENOSPC if a very large allocation is attempted.  Some xfstests
stress low free space situations by fallocating almost all the free
space in the volume.

This adds an allocation helper function that finds the biggest free
extent to satisfy an allocation, psosibly after trying to get more free
extents from the server.  It looks for previous extents in the index of
extents by length.  This builds on the previously added item and extent
_prev operations.

Allocators need to then know the size of the allocation they got instead
of assuming they got what they asked for.  The server can also return a
smaller extent so it needs to communicate the extent length, not just
its start.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2018-06-29 14:42:06 -07:00
committed by Zach Brown
parent 04660dbfee
commit 2efba47b77
6 changed files with 143 additions and 86 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kmod/src/data.c
+98 -67
View File
@@ -58,6 +58,20 @@
* - need trans around each bulk alloc
*/
/*
* The largest extent that we'll store in a single item. This will
* determine the granularity of interleaved concurrent allocations on a
* node. Sequential max length allocations could still see contiguous
* physical extent allocations. It limits the amount of IO needed to
* invalidate a lock. And it determines the granularity of parallel
* writes to a file between nodes.
*/
#define MAX_EXTENT_BLOCKS (8ULL * 1024 * 1024 >> SCOUTFS_BLOCK_SHIFT)
/*
* We ask for a fixed size from the server today.
*/
#define SERVER_ALLOC_BLOCKS (MAX_EXTENT_BLOCKS * 8)
struct data_info {
struct rw_semaphore alloc_rwsem;
};
@@ -399,14 +413,16 @@ int scoutfs_data_truncate_items(struct super_block *sb, struct inode *inode,
return ret;
}
static int get_server_extent(struct super_block *sb, u64 len)
static int get_server_extent(struct super_block *sb)
{
struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
struct scoutfs_extent ext;
u64 start;
u64 len;
int ret;
ret = scoutfs_client_alloc_extent(sb, len, &start);
ret = scoutfs_client_alloc_extent(sb, SERVER_ALLOC_BLOCKS,
&start, &len);
if (ret)
goto out;
@@ -420,6 +436,57 @@ out:
return ret;
}
/*
* Find a free extent to satisfy an allocation of at most @len blocks.
*
* Returns 0 and fills the caller's extent with a _BLKNO_TYPE extent if
* we found a match. It's len may be less than desired. No stored
* extents have been modified.
*
* Returns -errno on error and -ENOSPC if no free extents were found.
*
* The caller's extent is always clobbered.
*/
static int find_free_extent(struct super_block *sb, u64 len,
struct scoutfs_extent *ext)
{
struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
int ret;
len = min(len, MAX_EXTENT_BLOCKS);
for (;;) {
/* first try to find the first sufficient extent */
scoutfs_extent_init(ext, SCOUTFS_FREE_EXTENT_BLOCKS_TYPE,
sbi->node_id, 0, len, 0, 0);
ret = scoutfs_extent_next(sb, data_extent_io, ext,
sbi->node_id_lock);
/* if none big enough, look for last largest smaller */
if (ret == -ENOENT && len > 1)
ret = scoutfs_extent_prev(sb, data_extent_io, ext,
sbi->node_id_lock);
/* ask the server for more if we think it'll help */
if (ret == -ENOENT || ext->len < len) {
ret = get_server_extent(sb);
if (ret == 0)
continue;
}
/* use the extent we found or return errors */
break;
}
if (ret == 0)
scoutfs_extent_init(ext, SCOUTFS_FREE_EXTENT_BLKNO_TYPE,
sbi->node_id, ext->start,
min(ext->len, len), 0, 0);
trace_scoutfs_data_find_free_extent(sb, ext);
return ret;
}
/*
* The caller is writing to a logical block that doesn't have an
* allocated extent.
@@ -448,8 +515,6 @@ out:
* On success we update the caller's extent to the single block
* allocated extent for the logical block for use in block mapping.
*/
#define MAX_STREAMING_PREALLOC_BLOCKS ((u64)SCOUTFS_SEGMENT_BLOCKS)
#define SERVER_ALLOC_BLOCKS (MAX_STREAMING_PREALLOC_BLOCKS * 32)
static int alloc_block(struct super_block *sb, struct inode *inode,
struct scoutfs_extent *ext, u64 iblock, u64 len,
struct scoutfs_lock *lock)
@@ -474,30 +539,16 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
/* strictly contiguous extending writes will try to preallocate */
if (iblock > 1 && iblock == online)
len = min3(len, iblock, MAX_STREAMING_PREALLOC_BLOCKS);
len = min3(len, iblock, MAX_EXTENT_BLOCKS);
else
len = 1;
trace_scoutfs_data_alloc_block(sb, inode, ext, iblock, len,
online, offline);
scoutfs_extent_init(&fr, SCOUTFS_FREE_EXTENT_BLOCKS_TYPE,
sbi->node_id, 0, len, 0, 0);
ret = scoutfs_extent_next(sb, data_extent_io, &fr,
sbi->node_id_lock);
if (ret == -ENOENT) {
/* try to get allocation from the server if we're out */
ret = get_server_extent(sb, SERVER_ALLOC_BLOCKS);
if (ret == 0)
ret = scoutfs_extent_next(sb, data_extent_io, &fr,
sbi->node_id_lock);
}
if (ret) {
/* XXX should try to look for smaller free extents :/ */
if (ret == -ENOENT)
ret = -ENOSPC;
ret = find_free_extent(sb, len, &fr);
if (ret < 0)
goto out;
}
trace_scoutfs_data_alloc_block_next(sb, &fr);
@@ -505,9 +556,7 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
scoutfs_extent_init(&blk, SCOUTFS_FILE_EXTENT_TYPE, ino,
iblock, 1, fr.start, 0);
/* remove the free extent we're using */
scoutfs_extent_init(&fr, SCOUTFS_FREE_EXTENT_BLKNO_TYPE,
sbi->node_id, fr.start, len, 0, 0);
/* remove the free extent that we're allocating */
ret = scoutfs_extent_remove(sb, data_extent_io, &fr, sbi->node_id_lock);
if (ret)
goto out;
@@ -855,21 +904,14 @@ static int scoutfs_write_end(struct file *file, struct address_space *mapping,
}
/*
* Update one extent on behalf of fallocate.
* Allocate one extent on behalf of fallocate. The caller has given us
* the largest extent we can add, its flags, and the flags of an
* existing overlapping extent to remove.
*
* The caller has searched for the next extent that intersects with the
* region including first_block and last_block. The next extent will be
* zeroed if it wasn't found. We don't know the state of the offsets
* past the next extent.
*
* The caller has held transactions and acquired locks. We only ever
* make one extent modification here.
*
* If this returns 0 then the caller's extent is clobbered. It is set
* to the newly fallocated extent so that the caller can continue with
* the fallocate operation.
* We allocate the largest extent that we can and return its length or
* -errno.
*/
static int fallocate_one_extent(struct super_block *sb, u64 ino, u64 start,
static s64 fallocate_one_extent(struct super_block *sb, u64 ino, u64 start,
u64 len, u8 flags, u8 rem_flags,
struct scoutfs_lock *lock)
{
@@ -879,7 +921,7 @@ static int fallocate_one_extent(struct super_block *sb, u64 ino, u64 start,
struct scoutfs_extent fr;
bool add_rem = false;
bool add_fr = false;
int ret;
s64 ret;
if (WARN_ON_ONCE(len == 0) ||
WARN_ON_ONCE(start + len < start)) {
@@ -887,28 +929,9 @@ static int fallocate_one_extent(struct super_block *sb, u64 ino, u64 start,
goto out;
}
/* find a sufficiently large free extent */
scoutfs_extent_init(&fr, SCOUTFS_FREE_EXTENT_BLOCKS_TYPE,
sbi->node_id, 0, len, 0, 0);
ret = scoutfs_extent_next(sb, data_extent_io, &fr,
sbi->node_id_lock);
if (ret == -ENOENT) {
/* try to get allocation from the server if we're out */
ret = get_server_extent(sb, SERVER_ALLOC_BLOCKS);
if (ret == 0)
ret = scoutfs_extent_next(sb, data_extent_io, &fr,
sbi->node_id_lock);
/* XXX try to find smaller free extents */
}
if (ret < 0) {
if (ret == -ENOENT)
ret = -ENOSPC;
ret = find_free_extent(sb, len, &fr);
if (ret < 0)
goto out;
}
/* trim our allocation from the length indexed extent */
scoutfs_extent_init(&fr, SCOUTFS_FREE_EXTENT_BLKNO_TYPE,
sbi->node_id, fr.start, min(fr.len, len), 0, 0);
ret = scoutfs_extent_init(&fal, SCOUTFS_FILE_EXTENT_TYPE, ino,
start, fr.len, fr.start, flags);
@@ -931,6 +954,8 @@ static int fallocate_one_extent(struct super_block *sb, u64 ino, u64 start,
}
ret = scoutfs_extent_add(sb, data_extent_io, &fal, lock);
if (ret == 0)
ret = fal.len;
out:
scoutfs_extent_cleanup(ret < 0 && add_rem, scoutfs_extent_add, sb,
data_extent_io, &rem, lock,
@@ -961,7 +986,7 @@ long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
LIST_HEAD(ind_locks);
u64 last_block;
u64 iblock;
u64 blocks;
s64 blocks;
loff_t end;
u8 rem_flags;
u8 flags;
@@ -1003,7 +1028,7 @@ long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
iblock = offset >> SCOUTFS_BLOCK_SHIFT;
last_block = (offset + len - 1) >> SCOUTFS_BLOCK_SHIFT;
for (; iblock <= last_block; iblock = ext.start + ext.len) {
while(iblock <= last_block) {
scoutfs_extent_init(&ext, SCOUTFS_FILE_EXTENT_TYPE,
ino, iblock, 1, 0, 0);
@@ -1020,17 +1045,19 @@ long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
} else if (iblock < ext.start) {
/* sparse region until next extent */
blocks = min(blocks, ext.start - iblock);
blocks = min_t(u64, blocks, ext.start - iblock);
} else if (ext.map > 0) {
/* skip past an allocated extent */
blocks = min(blocks, (ext.start + ext.len) - iblock);
blocks = min_t(u64, blocks,
(ext.start + ext.len) - iblock);
iblock += blocks;
blocks = 0;
} else {
/* allocating a portion of an unallocated extent */
blocks = min(blocks, (ext.start + ext.len) - iblock);
blocks = min_t(u64, blocks,
(ext.start + ext.len) - iblock);
flags |= ext.flags;
rem_flags = ext.flags;
/* XXX corruption; why'd we store map == flags == 0? */
@@ -1047,9 +1074,13 @@ long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
if (blocks > 0) {
down_write(&datinf->alloc_rwsem);
ret = fallocate_one_extent(sb, ino, iblock, blocks,
flags, rem_flags, lock);
blocks = fallocate_one_extent(sb, ino, iblock, blocks,
flags, rem_flags, lock);
up_write(&datinf->alloc_rwsem);
if (blocks < 0)
ret = blocks;
else
ret = 0;
}
if (ret == 0 && !(mode & FALLOC_FL_KEEP_SIZE)) {
@@ -1068,7 +1099,7 @@ long scoutfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
iblock += blocks;
}
ret = 0;
out:
scoutfs_unlock(sb, lock, DLM_LOCK_EX);
mutex_unlock(&inode->i_mutex);