Messages in this thread | | | Date | Tue, 15 Nov 2011 18:23:44 +0800 | From | Cong Wang <> | Subject | Re: [Patch] tmpfs: add fallocate support |
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CC: Lennart Poettering <lennart@poettering.net> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
On 2011/11/15 16:42, Amerigo Wang wrote: > This patch adds fallocate support to tmpfs. I tested this patch > with the following test case, > > % sudo mount -t tmpfs -o size=100 tmpfs /mnt > % touch /mnt/foobar > % echo hi> /mnt/foobar > % fallocate -o 3 -l 5000 /mnt/foobar > fallocate: /mnt/foobar: fallocate failed: No space left on device > % fallocate -o 3 -l 3000 /mnt/foobar > % ls -l /mnt/foobar > -rw-rw-r-- 1 wangcong wangcong 3003 Nov 15 16:10 /mnt/foobar > % dd if=/dev/zero of=/mnt/foobar seek=3 bs=1 count=3000 > 3000+0 records in > 3000+0 records out > 3000 bytes (3.0 kB) copied, 0.0153224 s, 196 kB/s > % hexdump -C /mnt/foobar > 00000000 68 69 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 |hi..............| > 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| > * > 00000bb0 00 00 00 00 00 00 00 00 00 00 00 |...........| > 00000bbb > % cat /mnt/foobar > hi > > Signed-off-by: WANG Cong<amwang@redhat.com> > > --- > diff --git a/mm/shmem.c b/mm/shmem.c > index d672250..438b7b8 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -30,6 +30,7 @@ > #include<linux/mm.h> > #include<linux/export.h> > #include<linux/swap.h> > +#include<linux/falloc.h> > > static struct vfsmount *shm_mnt; > > @@ -1431,6 +1432,102 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, > return error; > } > > +static long shmem_fallocate(struct file *file, int mode, > + loff_t offset, loff_t len) > +{ > + struct inode *inode = file->f_path.dentry->d_inode; > + struct address_space *mapping = inode->i_mapping; > + struct shmem_inode_info *info = SHMEM_I(inode); > + struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); > + pgoff_t start = DIV_ROUND_UP(offset, PAGE_CACHE_SIZE); > + pgoff_t end = DIV_ROUND_UP((offset + len), PAGE_CACHE_SIZE); > + pgoff_t index = start; > + gfp_t gfp = mapping_gfp_mask(mapping); > + loff_t i_size = i_size_read(inode); > + struct page *page = NULL; > + int ret; > + > + if ((offset + len)<= i_size) > + return 0; > + > + if (!(mode& FALLOC_FL_KEEP_SIZE)) { > + ret = inode_newsize_ok(inode, (offset + len)); > + if (ret) > + return ret; > + } > + > + if (start == end) { > + if (!(mode& FALLOC_FL_KEEP_SIZE)) > + i_size_write(inode, offset + len); > + return 0; > + } > + > + if (shmem_acct_block(info->flags)) > + return -ENOSPC; > + > + if (sbinfo->max_blocks) { > + unsigned long blocks = (end - index) * BLOCKS_PER_PAGE; > + if (blocks + percpu_counter_sum(&sbinfo->used_blocks) > + >= sbinfo->max_blocks) { > + ret = -ENOSPC; > + goto unacct; > + } > + } > + > + while (index< end) { > + if (sbinfo->max_blocks) > + percpu_counter_add(&sbinfo->used_blocks, BLOCKS_PER_PAGE); > + > + page = shmem_alloc_page(gfp, info, index); > + if (!page) { > + ret = -ENOMEM; > + goto decused; > + } > + > + SetPageSwapBacked(page); > + __set_page_locked(page); > + ret = mem_cgroup_cache_charge(page, current->mm, > + gfp& GFP_RECLAIM_MASK); > + if (!ret) > + ret = shmem_add_to_page_cache(page, mapping, index, > + gfp, NULL); > + if (ret) > + goto unlock; > + lru_cache_add_anon(page); > + > + spin_lock(&info->lock); > + info->alloced++; > + inode->i_blocks += BLOCKS_PER_PAGE; > + inode->i_ctime = inode->i_mtime = CURRENT_TIME; > + shmem_recalc_inode(inode); > + spin_unlock(&info->lock); > + > + clear_highpage(page); > + flush_dcache_page(page); > + SetPageUptodate(page); > + unlock_page(page); > + page_cache_release(page); > + cond_resched(); > + index++; > + if (!(mode& FALLOC_FL_KEEP_SIZE)) > + i_size_write(inode, index<< PAGE_CACHE_SHIFT); > + } > + > + goto unacct; > + > +unlock: > + if (page) { > + unlock_page(page); > + page_cache_release(page); > + } > +decused: > + if (sbinfo->max_blocks) > + percpu_counter_sub(&sbinfo->used_blocks, BLOCKS_PER_PAGE); > +unacct: > + shmem_unacct_blocks(info->flags, 1); > + return ret; > +} > + > static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) > { > struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); > @@ -2286,6 +2383,7 @@ static const struct file_operations shmem_file_operations = { > .fsync = noop_fsync, > .splice_read = shmem_file_splice_read, > .splice_write = generic_file_splice_write, > + .fallocate = shmem_fallocate, > #endif > }; >
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