4 files changed, 465 insertions, 0 deletions

diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt
new file mode 100644
index 000000000000..1e3defcfe50b
--- /dev/null
+++ b/Documentation/filesystems/fiemap.txt
@@ -0,0 +1,228 @@
+============
+Fiemap Ioctl
+============
+
+The fiemap ioctl is an efficient method for userspace to get file
+extent mappings. Instead of block-by-block mapping (such as bmap), fiemap
+returns a list of extents.
+
+
+Request Basics
+--------------
+
+A fiemap request is encoded within struct fiemap:
+
+struct fiemap {
+        __u64   fm_start;        /* logical offset (inclusive) at
+                                  * which to start mapping (in) */
+        __u64   fm_length;       /* logical length of mapping which
+                                  * userspace cares about (in) */
+        __u32   fm_flags;        /* FIEMAP_FLAG_* flags for request (in/out) */
+        __u32   fm_mapped_extents; /* number of extents that were
+                                    * mapped (out) */
+        __u32   fm_extent_count; /* size of fm_extents array (in) */
+        __u32   fm_reserved;
+        struct fiemap_extent fm_extents[0]; /* array of mapped extents (out) */
+};
+
+
+fm_start, and fm_length specify the logical range within the file
+which the process would like mappings for. Extents returned mirror
+those on disk - that is, the logical offset of the 1st returned extent
+may start before fm_start, and the range covered by the last returned
+extent may end after fm_length. All offsets and lengths are in bytes.
+
+Certain flags to modify the way in which mappings are looked up can be
+set in fm_flags. If the kernel doesn't understand some particular
+flags, it will return EBADR and the contents of fm_flags will contain
+the set of flags which caused the error. If the kernel is compatible
+with all flags passed, the contents of fm_flags will be unmodified.
+It is up to userspace to determine whether rejection of a particular
+flag is fatal to it's operation. This scheme is intended to allow the
+fiemap interface to grow in the future but without losing
+compatibility with old software.
+
+fm_extent_count specifies the number of elements in the fm_extents[] array
+that can be used to return extents.  If fm_extent_count is zero, then the
+fm_extents[] array is ignored (no extents will be returned), and the
+fm_mapped_extents count will hold the number of extents needed in
+fm_extents[] to hold the file's current mapping.  Note that there is
+nothing to prevent the file from changing between calls to FIEMAP.
+
+The following flags can be set in fm_flags:
+
+* FIEMAP_FLAG_SYNC
+If this flag is set, the kernel will sync the file before mapping extents.
+
+* FIEMAP_FLAG_XATTR
+If this flag is set, the extents returned will describe the inodes
+extended attribute lookup tree, instead of it's data tree.
+
+
+Extent Mapping
+--------------
+
+Extent information is returned within the embedded fm_extents array
+which userspace must allocate along with the fiemap structure. The
+number of elements in the fiemap_extents[] array should be passed via
+fm_extent_count. The number of extents mapped by kernel will be
+returned via fm_mapped_extents. If the number of fiemap_extents
+allocated is less than would be required to map the requested range,
+the maximum number of extents that can be mapped in the fm_extent[]
+array will be returned and fm_mapped_extents will be equal to
+fm_extent_count. In that case, the last extent in the array will not
+complete the requested range and will not have the FIEMAP_EXTENT_LAST
+flag set (see the next section on extent flags).
+
+Each extent is described by a single fiemap_extent structure as
+returned in fm_extents.
+
+struct fiemap_extent {
+        __u64   fe_logical;  /* logical offset in bytes for the start of
+                              * the extent */
+        __u64   fe_physical; /* physical offset in bytes for the start
+                              * of the extent */
+        __u64   fe_length;   /* length in bytes for the extent */
+        __u64   fe_reserved64[2];
+        __u32   fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
+        __u32   fe_reserved[3];
+};
+
+All offsets and lengths are in bytes and mirror those on disk.  It is valid
+for an extents logical offset to start before the request or it's logical
+length to extend past the request.  Unless FIEMAP_EXTENT_NOT_ALIGNED is
+returned, fe_logical, fe_physical, and fe_length will be aligned to the
+block size of the file system.  With the exception of extents flagged as
+FIEMAP_EXTENT_MERGED, adjacent extents will not be merged.
+
+The fe_flags field contains flags which describe the extent returned.
+A special flag, FIEMAP_EXTENT_LAST is always set on the last extent in
+the file so that the process making fiemap calls can determine when no
+more extents are available, without having to call the ioctl again.
+
+Some flags are intentionally vague and will always be set in the
+presence of other more specific flags. This way a program looking for
+a general property does not have to know all existing and future flags
+which imply that property.
+
+For example, if FIEMAP_EXTENT_DATA_INLINE or FIEMAP_EXTENT_DATA_TAIL
+are set, FIEMAP_EXTENT_NOT_ALIGNED will also be set. A program looking
+for inline or tail-packed data can key on the specific flag. Software
+which simply cares not to try operating on non-aligned extents
+however, can just key on FIEMAP_EXTENT_NOT_ALIGNED, and not have to
+worry about all present and future flags which might imply unaligned
+data. Note that the opposite is not true - it would be valid for
+FIEMAP_EXTENT_NOT_ALIGNED to appear alone.
+
+* FIEMAP_EXTENT_LAST
+This is the last extent in the file. A mapping attempt past this
+extent will return nothing.
+
+* FIEMAP_EXTENT_UNKNOWN
+The location of this extent is currently unknown. This may indicate
+the data is stored on an inaccessible volume or that no storage has
+been allocated for the file yet.
+
+* FIEMAP_EXTENT_DELALLOC
+  - This will also set FIEMAP_EXTENT_UNKNOWN.
+Delayed allocation - while there is data for this extent, it's
+physical location has not been allocated yet.
+
+* FIEMAP_EXTENT_ENCODED
+This extent does not consist of plain filesystem blocks but is
+encoded (e.g. encrypted or compressed).  Reading the data in this
+extent via I/O to the block device will have undefined results.
+
+Note that it is *always* undefined to try to update the data
+in-place by writing to the indicated location without the
+assistance of the filesystem, or to access the data using the
+information returned by the FIEMAP interface while the filesystem
+is mounted.  In other words, user applications may only read the
+extent data via I/O to the block device while the filesystem is
+unmounted, and then only if the FIEMAP_EXTENT_ENCODED flag is
+clear; user applications must not try reading or writing to the
+filesystem via the block device under any other circumstances.
+
+* FIEMAP_EXTENT_DATA_ENCRYPTED
+  - This will also set FIEMAP_EXTENT_ENCODED
+The data in this extent has been encrypted by the file system.
+
+* FIEMAP_EXTENT_NOT_ALIGNED
+Extent offsets and length are not guaranteed to be block aligned.
+
+* FIEMAP_EXTENT_DATA_INLINE
+  This will also set FIEMAP_EXTENT_NOT_ALIGNED
+Data is located within a meta data block.
+
+* FIEMAP_EXTENT_DATA_TAIL
+  This will also set FIEMAP_EXTENT_NOT_ALIGNED
+Data is packed into a block with data from other files.
+
+* FIEMAP_EXTENT_UNWRITTEN
+Unwritten extent - the extent is allocated but it's data has not been
+initialized.  This indicates the extent's data will be all zero if read
+through the filesystem but the contents are undefined if read directly from
+the device.
+
+* FIEMAP_EXTENT_MERGED
+This will be set when a file does not support extents, i.e., it uses a block
+based addressing scheme.  Since returning an extent for each block back to
+userspace would be highly inefficient, the kernel will try to merge most
+adjacent blocks into 'extents'.
+
+
+VFS -> File System Implementation
+---------------------------------
+
+File systems wishing to support fiemap must implement a ->fiemap callback on
+their inode_operations structure. The fs ->fiemap call is responsible for
+defining it's set of supported fiemap flags, and calling a helper function on
+each discovered extent:
+
+struct inode_operations {
+       ...
+
+       int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
+                     u64 len);
+
+->fiemap is passed struct fiemap_extent_info which describes the
+fiemap request:
+
+struct fiemap_extent_info {
+        unsigned int fi_flags;          /* Flags as passed from user */
+        unsigned int fi_extents_mapped; /* Number of mapped extents */
+        unsigned int fi_extents_max;    /* Size of fiemap_extent array */
+        struct fiemap_extent *fi_extents_start; /* Start of fiemap_extent array */
+};
+
+It is intended that the file system should not need to access any of this
+structure directly.
+
+
+Flag checking should be done at the beginning of the ->fiemap callback via the
+fiemap_check_flags() helper:
+
+int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
+
+The struct fieinfo should be passed in as recieved from ioctl_fiemap(). The
+set of fiemap flags which the fs understands should be passed via fs_flags. If
+fiemap_check_flags finds invalid user flags, it will place the bad values in
+fieinfo->fi_flags and return -EBADR. If the file system gets -EBADR, from
+fiemap_check_flags(), it should immediately exit, returning that error back to
+ioctl_fiemap().
+
+
+For each extent in the request range, the file system should call
+the helper function, fiemap_fill_next_extent():
+
+int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
+                            u64 phys, u64 len, u32 flags, u32 dev);
+
+fiemap_fill_next_extent() will use the passed values to populate the
+next free extent in the fm_extents array. 'General' extent flags will
+automatically be set from specific flags on behalf of the calling file
+system so that the userspace API is not broken.
+
+fiemap_fill_next_extent() returns 0 on success, and 1 when the
+user-supplied fm_extents array is full. If an error is encountered
+while copying the extent to user memory, -EFAULT will be returned.
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 7db32b3382d3..045d9601fbbd 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -16,6 +16,9 @@
 
 #include <asm/ioctls.h>
 
+/* So that the fiemap access checks can't overflow on 32 bit machines. */
+#define FIEMAP_MAX_EXTENTS      (UINT_MAX / sizeof(struct fiemap_extent))
+
 /**
  * vfs_ioctl - call filesystem specific ioctl methods
  * @filp:       open file to invoke ioctl method on
@@ -71,6 +74,156 @@ static int ioctl_fibmap(struct file *filp, int __user *p)
         return put_user(res, p);
 }
 
+/**
+ * fiemap_fill_next_extent - Fiemap helper function
+ * @fieinfo:    Fiemap context passed into ->fiemap
+ * @logical:    Extent logical start offset, in bytes
+ * @phys:       Extent physical start offset, in bytes
+ * @len:        Extent length, in bytes
+ * @flags:      FIEMAP_EXTENT flags that describe this extent
+ *
+ * Called from file system ->fiemap callback. Will populate extent
+ * info as passed in via arguments and copy to user memory. On
+ * success, extent count on fieinfo is incremented.
+ *
+ * Returns 0 on success, -errno on error, 1 if this was the last
+ * extent that will fit in user array.
+ */
+#define SET_UNKNOWN_FLAGS       (FIEMAP_EXTENT_DELALLOC)
+#define SET_NO_UNMOUNTED_IO_FLAGS       (FIEMAP_EXTENT_DATA_ENCRYPTED)
+#define SET_NOT_ALIGNED_FLAGS   (FIEMAP_EXTENT_DATA_TAIL|FIEMAP_EXTENT_DATA_INLINE)
+int fiemap_fill_next_extent(struct fiemap_extent_info *fieinfo, u64 logical,
+                            u64 phys, u64 len, u32 flags)
+{
+        struct fiemap_extent extent;
+        struct fiemap_extent *dest = fieinfo->fi_extents_start;
+
+        /* only count the extents */
+        if (fieinfo->fi_extents_max == 0) {
+                fieinfo->fi_extents_mapped++;
+                return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
+        }
+
+        if (fieinfo->fi_extents_mapped >= fieinfo->fi_extents_max)
+                return 1;
+
+        if (flags & SET_UNKNOWN_FLAGS)
+                flags |= FIEMAP_EXTENT_UNKNOWN;
+        if (flags & SET_NO_UNMOUNTED_IO_FLAGS)
+                flags |= FIEMAP_EXTENT_ENCODED;
+        if (flags & SET_NOT_ALIGNED_FLAGS)
+                flags |= FIEMAP_EXTENT_NOT_ALIGNED;
+
+        memset(&extent, 0, sizeof(extent));
+        extent.fe_logical = logical;
+        extent.fe_physical = phys;
+        extent.fe_length = len;
+        extent.fe_flags = flags;
+
+        dest += fieinfo->fi_extents_mapped;
+        if (copy_to_user(dest, &extent, sizeof(extent)))
+                return -EFAULT;
+
+        fieinfo->fi_extents_mapped++;
+        if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
+                return 1;
+        return (flags & FIEMAP_EXTENT_LAST) ? 1 : 0;
+}
+EXPORT_SYMBOL(fiemap_fill_next_extent);
+
+/**
+ * fiemap_check_flags - check validity of requested flags for fiemap
+ * @fieinfo:    Fiemap context passed into ->fiemap
+ * @fs_flags:   Set of fiemap flags that the file system understands
+ *
+ * Called from file system ->fiemap callback. This will compute the
+ * intersection of valid fiemap flags and those that the fs supports. That
+ * value is then compared against the user supplied flags. In case of bad user
+ * flags, the invalid values will be written into the fieinfo structure, and
+ * -EBADR is returned, which tells ioctl_fiemap() to return those values to
+ * userspace. For this reason, a return code of -EBADR should be preserved.
+ *
+ * Returns 0 on success, -EBADR on bad flags.
+ */
+int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags)
+{
+        u32 incompat_flags;
+
+        incompat_flags = fieinfo->fi_flags & ~(FIEMAP_FLAGS_COMPAT & fs_flags);
+        if (incompat_flags) {
+                fieinfo->fi_flags = incompat_flags;
+                return -EBADR;
+        }
+        return 0;
+}
+EXPORT_SYMBOL(fiemap_check_flags);
+
+static int fiemap_check_ranges(struct super_block *sb,
+                               u64 start, u64 len, u64 *new_len)
+{
+        *new_len = len;
+
+        if (len == 0)
+                return -EINVAL;
+
+        if (start > sb->s_maxbytes)
+                return -EFBIG;
+
+        /*
+         * Shrink request scope to what the fs can actually handle.
+         */
+        if ((len > sb->s_maxbytes) ||
+            (sb->s_maxbytes - len) < start)
+                *new_len = sb->s_maxbytes - start;
+
+        return 0;
+}
+
+static int ioctl_fiemap(struct file *filp, unsigned long arg)
+{
+        struct fiemap fiemap;
+        struct fiemap_extent_info fieinfo = { 0, };
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        struct super_block *sb = inode->i_sb;
+        u64 len;
+        int error;
+
+        if (!inode->i_op->fiemap)
+                return -EOPNOTSUPP;
+
+        if (copy_from_user(&fiemap, (struct fiemap __user *)arg,
+                           sizeof(struct fiemap)))
+                return -EFAULT;
+
+        if (fiemap.fm_extent_count > FIEMAP_MAX_EXTENTS)
+                return -EINVAL;
+
+        error = fiemap_check_ranges(sb, fiemap.fm_start, fiemap.fm_length,
+                                    &len);
+        if (error)
+                return error;
+
+        fieinfo.fi_flags = fiemap.fm_flags;
+        fieinfo.fi_extents_max = fiemap.fm_extent_count;
+        fieinfo.fi_extents_start = (struct fiemap_extent *)(arg + sizeof(fiemap));
+
+        if (fiemap.fm_extent_count != 0 &&
+            !access_ok(VERIFY_WRITE, fieinfo.fi_extents_start,
+                       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
+                return -EFAULT;
+
+        if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
+                filemap_write_and_wait(inode->i_mapping);
+
+        error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start, len);
+        fiemap.fm_flags = fieinfo.fi_flags;
+        fiemap.fm_mapped_extents = fieinfo.fi_extents_mapped;
+        if (copy_to_user((char *)arg, &fiemap, sizeof(fiemap)))
+                error = -EFAULT;
+
+        return error;
+}
+
 static int file_ioctl(struct file *filp, unsigned int cmd,
                 unsigned long arg)
 {
@@ -80,6 +233,8 @@ static int file_ioctl(struct file *filp, unsigned int cmd,
         switch (cmd) {
         case FIBMAP:
                 return ioctl_fibmap(filp, p);
+        case FS_IOC_FIEMAP:
+                return ioctl_fiemap(filp, arg);
         case FIGETBSZ:
                 return put_user(inode->i_sb->s_blocksize, p);
         case FIONREAD:
diff --git a/include/linux/fiemap.h b/include/linux/fiemap.h
new file mode 100644
index 000000000000..671decbd2aeb
--- /dev/null
+++ b/include/linux/fiemap.h
@@ -0,0 +1,64 @@
+/*
+ * FS_IOC_FIEMAP ioctl infrastructure.
+ *
+ * Some portions copyright (C) 2007 Cluster File Systems, Inc
+ *
+ * Authors: Mark Fasheh <mfasheh@suse.com>
+ *          Kalpak Shah <kalpak.shah@sun.com>
+ *          Andreas Dilger <adilger@sun.com>
+ */
+
+#ifndef _LINUX_FIEMAP_H
+#define _LINUX_FIEMAP_H
+
+struct fiemap_extent {
+        __u64 fe_logical;  /* logical offset in bytes for the start of
+                            * the extent from the beginning of the file */
+        __u64 fe_physical; /* physical offset in bytes for the start
+                            * of the extent from the beginning of the disk */
+        __u64 fe_length;   /* length in bytes for this extent */
+        __u64 fe_reserved64[2];
+        __u32 fe_flags;    /* FIEMAP_EXTENT_* flags for this extent */
+        __u32 fe_reserved[3];
+};
+
+struct fiemap {
+        __u64 fm_start;         /* logical offset (inclusive) at
+                                 * which to start mapping (in) */
+        __u64 fm_length;        /* logical length of mapping which
+                                 * userspace wants (in) */
+        __u32 fm_flags;         /* FIEMAP_FLAG_* flags for request (in/out) */
+        __u32 fm_mapped_extents;/* number of extents that were mapped (out) */
+        __u32 fm_extent_count;  /* size of fm_extents array (in) */
+        __u32 fm_reserved;
+        struct fiemap_extent fm_extents[0]; /* array of mapped extents (out) */
+};
+
+#define FIEMAP_MAX_OFFSET       (~0ULL)
+
+#define FIEMAP_FLAG_SYNC        0x00000001 /* sync file data before map */
+#define FIEMAP_FLAG_XATTR       0x00000002 /* map extended attribute tree */
+
+#define FIEMAP_FLAGS_COMPAT     (FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR)
+
+#define FIEMAP_EXTENT_LAST              0x00000001 /* Last extent in file. */
+#define FIEMAP_EXTENT_UNKNOWN           0x00000002 /* Data location unknown. */
+#define FIEMAP_EXTENT_DELALLOC          0x00000004 /* Location still pending.
+                                                    * Sets EXTENT_UNKNOWN. */
+#define FIEMAP_EXTENT_ENCODED           0x00000008 /* Data can not be read
+                                                    * while fs is unmounted */
+#define FIEMAP_EXTENT_DATA_ENCRYPTED    0x00000080 /* Data is encrypted by fs.
+                                                    * Sets EXTENT_NO_BYPASS. */
+#define FIEMAP_EXTENT_NOT_ALIGNED       0x00000100 /* Extent offsets may not be
+                                                    * block aligned. */
+#define FIEMAP_EXTENT_DATA_INLINE       0x00000200 /* Data mixed with metadata.
+                                                    * Sets EXTENT_NOT_ALIGNED.*/
+#define FIEMAP_EXTENT_DATA_TAIL         0x00000400 /* Multiple files in block.
+                                                    * Sets EXTENT_NOT_ALIGNED.*/
+#define FIEMAP_EXTENT_UNWRITTEN         0x00000800 /* Space allocated, but
+                                                    * no data (i.e. zero). */
+#define FIEMAP_EXTENT_MERGED            0x00001000 /* File does not natively
+                                                    * support extents. Result
+                                                    * merged for efficiency. */
+
+#endif /* _LINUX_FIEMAP_H */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 580b513668fe..194fb237a307 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -231,6 +231,7 @@ extern int dir_notify_enable;
 #define FS_IOC_SETFLAGS                 _IOW('f', 2, long)
 #define FS_IOC_GETVERSION               _IOR('v', 1, long)
 #define FS_IOC_SETVERSION               _IOW('v', 2, long)
+#define FS_IOC_FIEMAP                   _IOWR('f', 11, struct fiemap)
 #define FS_IOC32_GETFLAGS               _IOR('f', 1, int)
 #define FS_IOC32_SETFLAGS               _IOW('f', 2, int)
 #define FS_IOC32_GETVERSION             _IOR('v', 1, int)
@@ -291,6 +292,7 @@ extern int dir_notify_enable;
 #include <linux/mutex.h>
 #include <linux/capability.h>
 #include <linux/semaphore.h>
+#include <linux/fiemap.h>
 
 #include <asm/atomic.h>
 #include <asm/byteorder.h>
@@ -1179,6 +1181,20 @@ extern void dentry_unhash(struct dentry *dentry);
 extern int file_permission(struct file *, int);
 
 /*
+ * VFS FS_IOC_FIEMAP helper definitions.
+ */
+struct fiemap_extent_info {
+        unsigned int fi_flags;          /* Flags as passed from user */
+        unsigned int fi_extents_mapped; /* Number of mapped extents */
+        unsigned int fi_extents_max;    /* Size of fiemap_extent array */
+        struct fiemap_extent *fi_extents_start; /* Start of fiemap_extent
+                                                 * array */
+};
+int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
+                            u64 phys, u64 len, u32 flags);
+int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
+
+/*
  * File types
  *
  * NOTE! These match bits 12..15 of stat.st_mode
@@ -1287,6 +1303,8 @@ struct inode_operations {
         void (*truncate_range)(struct inode *, loff_t, loff_t);
         long (*fallocate)(struct inode *inode, int mode, loff_t offset,
                           loff_t len);
+        int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
+                      u64 len);
 };
 
 struct seq_file;