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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-10 04:38:34 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-10 04:38:34 +0300
commit123a28d8b522b03dd97c1f791245924088616ac0 (patch)
treecda2f2b6ea4f4f31e0d23cb21b519ebf73cad82d
parent373ee21eecebc5c06786a803d99661a3657afcc7 (diff)
parent5726b27b09cc92452b543764899a07e7c8037edd (diff)
downloadlinux-123a28d8b522b03dd97c1f791245924088616ac0.tar.xz
Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull ext2 fix from Jan Kara: "Fix for DAX on ext2" * 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: ext2: Add locking for DAX faults
-rw-r--r--fs/ext2/ext2.h11
-rw-r--r--fs/ext2/file.c84
-rw-r--r--fs/ext2/inode.c10
-rw-r--r--fs/ext2/super.c3
4 files changed, 104 insertions, 4 deletions
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 8d15febd0aa3..4c69c94cafd8 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -684,6 +684,9 @@ struct ext2_inode_info {
struct rw_semaphore xattr_sem;
#endif
rwlock_t i_meta_lock;
+#ifdef CONFIG_FS_DAX
+ struct rw_semaphore dax_sem;
+#endif
/*
* truncate_mutex is for serialising ext2_truncate() against
@@ -699,6 +702,14 @@ struct ext2_inode_info {
#endif
};
+#ifdef CONFIG_FS_DAX
+#define dax_sem_down_write(ext2_inode) down_write(&(ext2_inode)->dax_sem)
+#define dax_sem_up_write(ext2_inode) up_write(&(ext2_inode)->dax_sem)
+#else
+#define dax_sem_down_write(ext2_inode)
+#define dax_sem_up_write(ext2_inode)
+#endif
+
/*
* Inode dynamic state flags
*/
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 1982c3f11aec..11a42c5a09ae 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -27,27 +27,103 @@
#include "acl.h"
#ifdef CONFIG_FS_DAX
+/*
+ * The lock ordering for ext2 DAX fault paths is:
+ *
+ * mmap_sem (MM)
+ * sb_start_pagefault (vfs, freeze)
+ * ext2_inode_info->dax_sem
+ * address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
+ * ext2_inode_info->truncate_mutex
+ *
+ * The default page_lock and i_size verification done by non-DAX fault paths
+ * is sufficient because ext2 doesn't support hole punching.
+ */
static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return dax_fault(vma, vmf, ext2_get_block, NULL);
+ struct inode *inode = file_inode(vma->vm_file);
+ struct ext2_inode_info *ei = EXT2_I(inode);
+ int ret;
+
+ if (vmf->flags & FAULT_FLAG_WRITE) {
+ sb_start_pagefault(inode->i_sb);
+ file_update_time(vma->vm_file);
+ }
+ down_read(&ei->dax_sem);
+
+ ret = __dax_fault(vma, vmf, ext2_get_block, NULL);
+
+ up_read(&ei->dax_sem);
+ if (vmf->flags & FAULT_FLAG_WRITE)
+ sb_end_pagefault(inode->i_sb);
+ return ret;
}
static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned int flags)
{
- return dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block, NULL);
+ struct inode *inode = file_inode(vma->vm_file);
+ struct ext2_inode_info *ei = EXT2_I(inode);
+ int ret;
+
+ if (flags & FAULT_FLAG_WRITE) {
+ sb_start_pagefault(inode->i_sb);
+ file_update_time(vma->vm_file);
+ }
+ down_read(&ei->dax_sem);
+
+ ret = __dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block, NULL);
+
+ up_read(&ei->dax_sem);
+ if (flags & FAULT_FLAG_WRITE)
+ sb_end_pagefault(inode->i_sb);
+ return ret;
}
static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return dax_mkwrite(vma, vmf, ext2_get_block, NULL);
+ struct inode *inode = file_inode(vma->vm_file);
+ struct ext2_inode_info *ei = EXT2_I(inode);
+ int ret;
+
+ sb_start_pagefault(inode->i_sb);
+ file_update_time(vma->vm_file);
+ down_read(&ei->dax_sem);
+
+ ret = __dax_mkwrite(vma, vmf, ext2_get_block, NULL);
+
+ up_read(&ei->dax_sem);
+ sb_end_pagefault(inode->i_sb);
+ return ret;
+}
+
+static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ struct inode *inode = file_inode(vma->vm_file);
+ struct ext2_inode_info *ei = EXT2_I(inode);
+ int ret = VM_FAULT_NOPAGE;
+ loff_t size;
+
+ sb_start_pagefault(inode->i_sb);
+ file_update_time(vma->vm_file);
+ down_read(&ei->dax_sem);
+
+ /* check that the faulting page hasn't raced with truncate */
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (vmf->pgoff >= size)
+ ret = VM_FAULT_SIGBUS;
+
+ up_read(&ei->dax_sem);
+ sb_end_pagefault(inode->i_sb);
+ return ret;
}
static const struct vm_operations_struct ext2_dax_vm_ops = {
.fault = ext2_dax_fault,
.pmd_fault = ext2_dax_pmd_fault,
.page_mkwrite = ext2_dax_mkwrite,
- .pfn_mkwrite = dax_pfn_mkwrite,
+ .pfn_mkwrite = ext2_dax_pfn_mkwrite,
};
static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index c60a248c640c..0aa9bf6e6e53 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1085,6 +1085,7 @@ static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int de
ext2_free_data(inode, p, q);
}
+/* dax_sem must be held when calling this function */
static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
{
__le32 *i_data = EXT2_I(inode)->i_data;
@@ -1100,6 +1101,10 @@ static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
blocksize = inode->i_sb->s_blocksize;
iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
+#ifdef CONFIG_FS_DAX
+ WARN_ON(!rwsem_is_locked(&ei->dax_sem));
+#endif
+
n = ext2_block_to_path(inode, iblock, offsets, NULL);
if (n == 0)
return;
@@ -1185,7 +1190,10 @@ static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
return;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
return;
+
+ dax_sem_down_write(EXT2_I(inode));
__ext2_truncate_blocks(inode, offset);
+ dax_sem_up_write(EXT2_I(inode));
}
static int ext2_setsize(struct inode *inode, loff_t newsize)
@@ -1213,8 +1221,10 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
if (error)
return error;
+ dax_sem_down_write(EXT2_I(inode));
truncate_setsize(inode, newsize);
__ext2_truncate_blocks(inode, newsize);
+ dax_sem_up_write(EXT2_I(inode));
inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
if (inode_needs_sync(inode)) {
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 900e19cf9ef6..3a71cea68420 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -192,6 +192,9 @@ static void init_once(void *foo)
init_rwsem(&ei->xattr_sem);
#endif
mutex_init(&ei->truncate_mutex);
+#ifdef CONFIG_FS_DAX
+ init_rwsem(&ei->dax_sem);
+#endif
inode_init_once(&ei->vfs_inode);
}