Commit d4686d56 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: avoid balanc_fs during evict_inode

1. Background

Previously, if f2fs tries to move data blocks of an *evicting* inode during the
cleaning process, it stops the process incompletely and then restarts the whole
process, since it needs a locked inode to grab victim data pages in its address
space. In order to get a locked inode, iget_locked() by f2fs_iget() is normally
used, but, it waits if the inode is on freeing.

So, here is a deadlock scenario.
1. f2fs_evict_inode()       <- inode "A"
  2. f2fs_balance_fs()
    3. f2fs_gc()
      4. gc_data_segment()
        5. f2fs_iget()      <- inode "A" too!

If step #1 and #5 treat a same inode "A", step #5 would fall into deadlock since
the inode "A" is on freeing. In order to resolve this, f2fs_iget_nowait() which
skips __wait_on_freeing_inode() was introduced in step #5

, and stops f2fs_gc()
to complete f2fs_evict_inode().

1. f2fs_evict_inode()           <- inode "A"
  2. f2fs_balance_fs()
    3. f2fs_gc()
      4. gc_data_segment()
        5. f2fs_iget_nowait()   <- inode "A", then stop f2fs_gc() w/ -ENOENT

2. Problem and Solution

In the above scenario, however, f2fs cannot finish f2fs_evict_inode() only if:
 o there are not enough free sections, and
 o f2fs_gc() tries to move data blocks of the *evicting* inode repeatedly.

So, the final solution is to use f2fs_iget() and remove f2fs_balance_fs() in
f2fs_evict_inode().
The f2fs_evict_inode() actually truncates all the data and node blocks, which
means that it doesn't produce any dirty node pages accordingly.
So, we don't need to do f2fs_balance_fs() in practical.
Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent 369a708c
......@@ -847,7 +847,6 @@ long f2fs_ioctl(struct file *, unsigned int, unsigned long);
* inode.c
*/
void f2fs_set_inode_flags(struct inode *);
struct inode *f2fs_iget_nowait(struct super_block *, unsigned long);
struct inode *f2fs_iget(struct super_block *, unsigned long);
void update_inode(struct inode *, struct page *);
int f2fs_write_inode(struct inode *, struct writeback_control *);
......
......@@ -298,8 +298,6 @@ void f2fs_truncate(struct inode *inode)
inode->i_mtime = inode->i_ctime = CURRENT_TIME;
mark_inode_dirty(inode);
}
f2fs_balance_fs(F2FS_SB(inode->i_sb));
}
static int f2fs_getattr(struct vfsmount *mnt,
......@@ -356,6 +354,7 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
attr->ia_size != i_size_read(inode)) {
truncate_setsize(inode, attr->ia_size);
f2fs_truncate(inode);
f2fs_balance_fs(F2FS_SB(inode->i_sb));
}
__setattr_copy(inode, attr);
......
......@@ -579,7 +579,7 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
ofs_in_node = le16_to_cpu(entry->ofs_in_node);
if (phase == 2) {
inode = f2fs_iget_nowait(sb, dni.ino);
inode = f2fs_iget(sb, dni.ino);
if (IS_ERR(inode))
continue;
......
......@@ -16,11 +16,6 @@
#include "f2fs.h"
#include "node.h"
struct f2fs_iget_args {
u64 ino;
int on_free;
};
void f2fs_set_inode_flags(struct inode *inode)
{
unsigned int flags = F2FS_I(inode)->i_flags;
......@@ -40,34 +35,6 @@ void f2fs_set_inode_flags(struct inode *inode)
inode->i_flags |= S_DIRSYNC;
}
static int f2fs_iget_test(struct inode *inode, void *data)
{
struct f2fs_iget_args *args = data;
if (inode->i_ino != args->ino)
return 0;
if (inode->i_state & (I_FREEING | I_WILL_FREE)) {
args->on_free = 1;
return 0;
}
return 1;
}
struct inode *f2fs_iget_nowait(struct super_block *sb, unsigned long ino)
{
struct f2fs_iget_args args = {
.ino = ino,
.on_free = 0
};
struct inode *inode = ilookup5(sb, ino, f2fs_iget_test, &args);
if (inode)
return inode;
if (!args.on_free)
return f2fs_iget(sb, ino);
return ERR_PTR(-ENOENT);
}
static int do_read_inode(struct inode *inode)
{
struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
......
......@@ -226,7 +226,7 @@ static void check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
f2fs_put_page(node_page, 1);
/* Deallocate previous index in the node page */
inode = f2fs_iget_nowait(sbi->sb, ino);
inode = f2fs_iget(sbi->sb, ino);
if (IS_ERR(inode))
return;
......
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