The current TRANS_START ioctl is problematic when the volume fills up
because a process can get ENOSPC on any operation that's supoosed to be
"contained" within its transaction without any prior warning. This
defines a new ioctl, TRANS_RESV_START, that checks and sets aside space
for the entire transaction, so that the process will get ENOSPC right
away.
The bytes_ioctl_trans_reserved is only checked and adjusted by the
TRANS_RESV_START ioctl; any write()s that follow will be allowed to use
up that reserved space. This is clearly imperfect (a mixture of an
ioctl transaction workload and a regular workload will violate the
reservations), but unavoidable with the current user transaction approach
because we don't know whether any given operation is contained by a
user transaction or not.
Signed-off-by: Sage Weil <sage@xxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 7 ++++
fs/btrfs/extent-tree.c | 59 +++++++++++++++++++++++++++++--
fs/btrfs/ioctl.c | 92 +++++++++++++++++++++++++++++++++++++++++++----
fs/btrfs/ioctl.h | 6 +++
4 files changed, 153 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b3959a1..14b7980 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -682,6 +682,9 @@ struct btrfs_space_info {
u64 bytes_delalloc; /* number of bytes currently reserved for
delayed allocation */
+ u64 bytes_ioctl_trans_reserved; /* number of bytes reserved by ioctl
+ transactions */
+
int full; /* indicates that we cannot allocate any more
chunks for this space */
int force_alloc; /* set if we need to force a chunk alloc for
@@ -2036,6 +2039,10 @@ int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
u64 bytes);
void btrfs_free_reserved_data_space(struct btrfs_root *root,
struct inode *inode, u64 bytes);
+int btrfs_reserve_ioctl_trans_free_space(struct btrfs_root *root,
+ u64 bytes, u64 ops);
+void btrfs_unreserve_ioctl_trans_space(struct btrfs_root *root,
+ u64 bytes, u64 ops);
void btrfs_delalloc_reserve_space(struct btrfs_root *root, struct inode *inode,
u64 bytes);
void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c190bdb..d6316f8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2670,6 +2670,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
found->bytes_reserved = 0;
found->bytes_readonly = 0;
found->bytes_delalloc = 0;
+ found->bytes_ioctl_trans_reserved = 0;
found->full = 0;
found->force_alloc = 0;
*space_info = found;
@@ -3129,6 +3130,14 @@ static int __alloc_chunk(struct btrfs_root *root, u64 bytes)
return ret;
}
+/*
+ * if @inode is defined, reserve bytes on that inode. otherwise, we
+ * are reserving the space for an ioctl transaction, and need to
+ * subtract off other ioctl reserved space too. we _only_ check ioctl
+ * reserved space here: the write() that follows needs to be able to
+ * use it, and we don't know which writes "belong" to which ioctl
+ * transactions.
+ */
int btrfs_check_data_free_space_info(struct btrfs_root *root,
struct btrfs_space_info *data_sinfo,
u64 bytes,
@@ -3142,6 +3151,7 @@ again:
if (data_sinfo->total_bytes - data_sinfo->bytes_used -
data_sinfo->bytes_delalloc - data_sinfo->bytes_reserved -
data_sinfo->bytes_pinned - data_sinfo->bytes_readonly -
+ (inode ? 0 : data_sinfo->bytes_ioctl_trans_reserved) -
data_sinfo->bytes_may_use - data_sinfo->bytes_super < bytes) {
struct btrfs_trans_handle *trans;
@@ -3160,7 +3170,8 @@ again:
spin_unlock(&data_sinfo->lock);
/* commit the current transaction and try again */
- if (!committed && !root->fs_info->open_ioctl_trans) {
+ if (!committed &&
+ (!inode || !root->fs_info->open_ioctl_trans)) {
committed = 1;
trans = btrfs_join_transaction(root, 1);
if (!trans)
@@ -3184,8 +3195,12 @@ again:
(unsigned long long)data_sinfo->total_bytes);
return -ENOSPC;
}
- data_sinfo->bytes_may_use += bytes;
- BTRFS_I(inode)->reserved_bytes += bytes;
+ if (inode) {
+ data_sinfo->bytes_may_use += bytes;
+ BTRFS_I(inode)->reserved_bytes += bytes;
+ } else {
+ data_sinfo->bytes_ioctl_trans_reserved += bytes;
+ }
spin_unlock(&data_sinfo->lock);
return 0;
}
@@ -3215,6 +3230,44 @@ int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
return btrfs_check_data_free_space_info(root, data_sinfo, bytes, inode);
}
+int btrfs_reserve_ioctl_trans_free_space(struct btrfs_root *root, u64 bytes,
+ u64 ops)
+{
+ struct btrfs_space_info *data_sinfo;
+ u64 alloc_target;
+ int ret;
+
+ /* make sure bytes are sectorsize aligned */
+ bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
+ bytes += calculate_bytes_needed(root, ops * 5);
+
+ alloc_target = btrfs_get_alloc_profile(root, 1);
+ data_sinfo = __find_space_info(root->fs_info, alloc_target);
+ ret = btrfs_check_data_free_space_info(root, data_sinfo, bytes, NULL);
+ if (ret)
+ return ret;
+ return 0;
+}
+
+void btrfs_unreserve_ioctl_trans_space(struct btrfs_root *root,
+ u64 bytes, u64 ops)
+{
+ struct btrfs_space_info *data_sinfo;
+ u64 alloc_target;
+
+ /* make sure bytes are sectorsize aligned */
+ bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
+ bytes += calculate_bytes_needed(root, ops * 5);
+
+ if (bytes) {
+ alloc_target = btrfs_get_alloc_profile(root, 1);
+ data_sinfo = __find_space_info(root->fs_info, alloc_target);
+ spin_lock(&data_sinfo->lock);
+ data_sinfo->bytes_ioctl_trans_reserved -= bytes;
+ spin_unlock(&data_sinfo->lock);
+ }
+}
+
/*
* if there was an error for whatever reason after calling
* btrfs_check_data_free_space, call this so we can cleanup the counters.
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9a780c8..dd4fde1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1227,11 +1227,76 @@ static long btrfs_ioctl_clone_range(struct file *file, void __user *argp)
* basically own the machine, and have a very in depth understanding
* of all the possible deadlocks and enospc problems.
*/
+struct btrfs_ioctl_trans {
+ struct btrfs_trans_handle *trans;
+ u64 reserved_bytes, reserved_ops;
+};
+
+static long btrfs_ioctl_trans_resv_start(struct file *file, void __user *argp)
+{
+ struct inode *inode = fdentry(file)->d_inode;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_ioctl_trans *ioctl_trans;
+ struct btrfs_ioctl_trans_resv_start resv;
+ int ret;
+
+ ret = -EPERM;
+ if (!capable(CAP_SYS_ADMIN))
+ goto out;
+
+ ret = -EINPROGRESS;
+ if (file->private_data)
+ goto out;
+
+ ret = -EFAULT;
+ if (copy_from_user(&resv, argp, sizeof(resv)))
+ goto out;
+
+ ret = mnt_want_write(file->f_path.mnt);
+ if (ret)
+ goto out;
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ root->fs_info->open_ioctl_trans++;
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ ret = btrfs_reserve_ioctl_trans_free_space(root, resv.bytes, resv.ops);
+ if (ret)
+ goto out_drop;
+
+ ret = -ENOMEM;
+ ioctl_trans = kzalloc(sizeof(*ioctl_trans), GFP_KERNEL);
+ if (!ioctl_trans)
+ goto out_free_bytes;
+
+ ioctl_trans->trans = btrfs_start_ioctl_transaction(root, 0);
+ if (!ioctl_trans->trans)
+ goto out_free_ioctl_trans;
+
+ ioctl_trans->reserved_bytes = resv.bytes;
+ ioctl_trans->reserved_ops = resv.ops;
+ file->private_data = ioctl_trans;
+ return 0;
+
+out_free_ioctl_trans:
+ kfree(ioctl_trans);
+out_free_bytes:
+ btrfs_unreserve_ioctl_trans_space(root, resv.bytes, resv.ops);
+out_drop:
+ mutex_lock(&root->fs_info->trans_mutex);
+ root->fs_info->open_ioctl_trans--;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ mnt_drop_write(file->f_path.mnt);
+out:
+ return ret;
+}
+
+
static long btrfs_ioctl_trans_start(struct file *file)
{
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_trans_handle *trans;
+ struct btrfs_ioctl_trans *ioctl_trans;
int ret;
ret = -EPERM;
@@ -1251,13 +1316,19 @@ static long btrfs_ioctl_trans_start(struct file *file)
mutex_unlock(&root->fs_info->trans_mutex);
ret = -ENOMEM;
- trans = btrfs_start_ioctl_transaction(root, 0);
- if (!trans)
+ ioctl_trans = kzalloc(sizeof(*ioctl_trans), GFP_KERNEL);
+ if (!ioctl_trans)
goto out_drop;
- file->private_data = trans;
+ ioctl_trans->trans = btrfs_start_ioctl_transaction(root, 0);
+ if (ioctl_trans->trans)
+ goto out_free_ioctl_trans;
+
+ file->private_data = ioctl_trans;
return 0;
+out_free_ioctl_trans:
+ kfree(ioctl_trans);
out_drop:
mutex_lock(&root->fs_info->trans_mutex);
root->fs_info->open_ioctl_trans--;
@@ -1277,14 +1348,17 @@ long btrfs_ioctl_trans_end(struct file *file)
{
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_trans_handle *trans;
+ struct btrfs_ioctl_trans *ioctl_trans;
- trans = file->private_data;
- if (!trans)
+ ioctl_trans = file->private_data;
+ if (!ioctl_trans)
return -EINVAL;
file->private_data = NULL;
- btrfs_end_transaction(trans, root);
+ btrfs_unreserve_ioctl_trans_space(root, ioctl_trans->reserved_bytes,
+ ioctl_trans->reserved_ops);
+ btrfs_end_transaction(ioctl_trans->trans, root);
+ kfree(ioctl_trans);
mutex_lock(&root->fs_info->trans_mutex);
root->fs_info->open_ioctl_trans--;
@@ -1327,6 +1401,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_clone(file, arg, 0, 0, 0);
case BTRFS_IOC_CLONE_RANGE:
return btrfs_ioctl_clone_range(file, argp);
+ case BTRFS_IOC_TRANS_RESV_START:
+ return btrfs_ioctl_trans_resv_start(file, argp);
case BTRFS_IOC_TRANS_START:
return btrfs_ioctl_trans_start(file);
case BTRFS_IOC_TRANS_END:
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index bc49914..9810980 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -48,6 +48,12 @@ struct btrfs_ioctl_clone_range_args {
* use by applications that know how to avoid the
* resulting deadlocks
*/
+/* check/reserve disk space for the transaction up-front */
+struct btrfs_ioctl_trans_resv_start {
+ __u64 bytes, ops;
+};
+#define BTRFS_IOC_TRANS_RESV_START _IOW(BTRFS_IOCTL_MAGIC, 5, \
+ struct btrfs_ioctl_trans_resv_start)
#define BTRFS_IOC_TRANS_START _IO(BTRFS_IOCTL_MAGIC, 6)
#define BTRFS_IOC_TRANS_END _IO(BTRFS_IOCTL_MAGIC, 7)
#define BTRFS_IOC_SYNC _IO(BTRFS_IOCTL_MAGIC, 8)
--
1.5.6.5
--
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