| Message ID | 20110620202030.577464178@bombadil.infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Christoph Hellwig <hch@infradead.org> writes: > Add a new rw_semaphore to protect bmap against truncate. Previous > i_alloc_sem was abused for this, but it's going away in this series. In FAT case, ->i_mutex was better. But, last time I saw, shmfs was using ->i_mutex to call ->bmap. So, this was chosen instead. I'm not checking current version yet though, if shmfs had change, we can use ->i_mutex. BTW, this patch looks good to me. Thanks. > Signed-off-by: Christoph Hellwig <hch@lst.de> > > Index: linux-2.6/fs/fat/inode.c > =================================================================== > --- linux-2.6.orig/fs/fat/inode.c 2011-06-20 21:28:19.707963855 +0200 > +++ linux-2.6/fs/fat/inode.c 2011-06-20 21:29:25.031293882 +0200 > @@ -224,9 +224,9 @@ static sector_t _fat_bmap(struct address > sector_t blocknr; > > /* fat_get_cluster() assumes the requested blocknr isn't truncated. */ > - down_read(&mapping->host->i_alloc_sem); > + down_read(&MSDOS_I(mapping->host)->truncate_lock); > blocknr = generic_block_bmap(mapping, block, fat_get_block); > - up_read(&mapping->host->i_alloc_sem); > + up_read(&MSDOS_I(mapping->host)->truncate_lock); > > return blocknr; > } > @@ -510,6 +510,8 @@ static struct inode *fat_alloc_inode(str > ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS); > if (!ei) > return NULL; > + > + init_rwsem(&ei->truncate_lock); > return &ei->vfs_inode; > } > > Index: linux-2.6/fs/fat/fat.h > =================================================================== > --- linux-2.6.orig/fs/fat/fat.h 2011-06-20 21:28:19.724630522 +0200 > +++ linux-2.6/fs/fat/fat.h 2011-06-20 21:29:25.034627215 +0200 > @@ -109,6 +109,7 @@ struct msdos_inode_info { > int i_attrs; /* unused attribute bits */ > loff_t i_pos; /* on-disk position of directory entry or 0 */ > struct hlist_node i_fat_hash; /* hash by i_location */ > + struct rw_semaphore truncate_lock; /* protect bmap against truncate */ > struct inode vfs_inode; > }; > > Index: linux-2.6/fs/fat/file.c > =================================================================== > --- linux-2.6.orig/fs/fat/file.c 2011-06-20 21:28:19.744630521 +0200 > +++ linux-2.6/fs/fat/file.c 2011-06-20 21:29:54.501292390 +0200 > @@ -429,8 +429,10 @@ int fat_setattr(struct dentry *dentry, s > } > > if (attr->ia_valid & ATTR_SIZE) { > + down_write(&MSDOS_I(inode)->truncate_lock); > truncate_setsize(inode, attr->ia_size); > fat_truncate_blocks(inode, attr->ia_size); > + up_write(&MSDOS_I(inode)->truncate_lock); > } > > setattr_copy(inode, attr); >
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> writes: > Christoph Hellwig <hch@infradead.org> writes: > >> Add a new rw_semaphore to protect bmap against truncate. Previous >> i_alloc_sem was abused for this, but it's going away in this series. > > In FAT case, ->i_mutex was better. But, last time I saw, shmfs was using > ->i_mutex to call ->bmap. So, this was chosen instead. > > I'm not checking current version yet though, if shmfs had change, we can > use ->i_mutex. It was swapfile. And unfortunately it doesn't have change. > BTW, this patch looks good to me.
On Wed, Jun 22, 2011 at 12:57:43AM +0900, OGAWA Hirofumi wrote: > Christoph Hellwig <hch@infradead.org> writes: > > > Add a new rw_semaphore to protect bmap against truncate. Previous > > i_alloc_sem was abused for this, but it's going away in this series. > > In FAT case, ->i_mutex was better. But, last time I saw, shmfs was using > ->i_mutex to call ->bmap. So, this was chosen instead. > > I'm not checking current version yet though, if shmfs had change, we can > use ->i_mutex. I tried that first, but it gives an instant deadlock when using a swapfile on fat. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: linux-2.6/fs/fat/inode.c =================================================================== --- linux-2.6.orig/fs/fat/inode.c 2011-06-20 21:28:19.707963855 +0200 +++ linux-2.6/fs/fat/inode.c 2011-06-20 21:29:25.031293882 +0200 @@ -224,9 +224,9 @@ static sector_t _fat_bmap(struct address sector_t blocknr; /* fat_get_cluster() assumes the requested blocknr isn't truncated. */ - down_read(&mapping->host->i_alloc_sem); + down_read(&MSDOS_I(mapping->host)->truncate_lock); blocknr = generic_block_bmap(mapping, block, fat_get_block); - up_read(&mapping->host->i_alloc_sem); + up_read(&MSDOS_I(mapping->host)->truncate_lock); return blocknr; } @@ -510,6 +510,8 @@ static struct inode *fat_alloc_inode(str ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS); if (!ei) return NULL; + + init_rwsem(&ei->truncate_lock); return &ei->vfs_inode; } Index: linux-2.6/fs/fat/fat.h =================================================================== --- linux-2.6.orig/fs/fat/fat.h 2011-06-20 21:28:19.724630522 +0200 +++ linux-2.6/fs/fat/fat.h 2011-06-20 21:29:25.034627215 +0200 @@ -109,6 +109,7 @@ struct msdos_inode_info { int i_attrs; /* unused attribute bits */ loff_t i_pos; /* on-disk position of directory entry or 0 */ struct hlist_node i_fat_hash; /* hash by i_location */ + struct rw_semaphore truncate_lock; /* protect bmap against truncate */ struct inode vfs_inode; }; Index: linux-2.6/fs/fat/file.c =================================================================== --- linux-2.6.orig/fs/fat/file.c 2011-06-20 21:28:19.744630521 +0200 +++ linux-2.6/fs/fat/file.c 2011-06-20 21:29:54.501292390 +0200 @@ -429,8 +429,10 @@ int fat_setattr(struct dentry *dentry, s } if (attr->ia_valid & ATTR_SIZE) { + down_write(&MSDOS_I(inode)->truncate_lock); truncate_setsize(inode, attr->ia_size); fat_truncate_blocks(inode, attr->ia_size); + up_write(&MSDOS_I(inode)->truncate_lock); } setattr_copy(inode, attr);
Add a new rw_semaphore to protect bmap against truncate. Previous i_alloc_sem was abused for this, but it's going away in this series. Signed-off-by: Christoph Hellwig <hch@lst.de> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html