Resize of a filesystem image does not work as expected. This has been
confusing and can have bad consequences as people have reported,
resizing the wrong filesystem.
Signed-off-by: David Sterba <dste...@suse.cz>
---
Documentation/btrfs-filesystem.asciidoc | 9 +++++++--
cmds-filesystem.c | 15 +++++++++++++++
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/Documentation/btrfs-filesystem.asciidoc
b/Documentation/btrfs-filesystem.asciidoc
index cefdc8ea93dd..630483d8c114 100644
--- a/Documentation/btrfs-filesystem.asciidoc
+++ b/Documentation/btrfs-filesystem.asciidoc
@@ -89,8 +89,13 @@ NOTE: the maximum allowable length shall be less than 256
chars
// Some wording are extracted by the resize2fs man page
*resize* [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max <path>::
-Resize a filesystem identified by <path> for the underlying device
-devid *online*. +
+Resize a mounted filesystem identified by directory <path>. A particular device
+can be resized by specifying a <devid>.
++
+If <path> is a file containing a btrfs image then resize does not work as
+expected and does not resize the image. This would resize the underlying
+filesytem instead.
++
The devid can be found with *btrfs filesystem show* and
defaults to 1 if not specified.
The <size> parameter specifies the new size of the filesystem.
diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index 188dbf0c48d2..d62aef6833ce 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -1234,6 +1234,7 @@ static int cmd_resize(int argc, char **argv)
int fd, res, len, e;
char *amount, *path;
DIR *dirstream = NULL;
+ struct stat st;
if (check_argc_exact(argc, 3))
usage(cmd_resize_usage);
@@ -1248,6 +1249,20 @@ static int cmd_resize(int argc, char **argv)
return 1;
}
+ res = stat(path, &st);
+ if (res < 0) {
+ fprintf(stderr, "ERROR: resize: cannot stat %s: %s\n",
+ path, strerror(errno));
+ return 1;
+ }
+ if (!S_ISDIR(st.st_mode)) {
+ fprintf(stderr,
+ "ERROR: resize works on mounted filesystems and accepts
only\n"
+ "directories as argument. Passing file containing a
btrfs image\n"
+ "would resize the underlying filesytem instead of the
image.\n");
+ return 1;
+ }
+
fd = open_file_or_dir(path, &dirstream);
if (fd < 0) {
fprintf(stderr, "ERROR: can't access '%s'\n", path);
--
2.1.3
--
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